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Letteratura scientifica selezionata sul tema "Polya groups"

Autore: Grafiati

Pubblicato: 25 gennaio 2025

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Articoli di riviste sul tema "Polya groups"

Olaniyan, Ademola Olatide, e Nadaraj Govender. "EFFECTIVENESS OF POLYA PROBLEM-SOLVING AND TARGET-TASK COLLABORATIVE LEARNING APPROACHES IN ELECTRICITY AMONGST HIGH SCHOOL PHYSICS STUDENTS". Journal of Baltic Science Education 17, n. 5 (15 ottobre 2018): 765–77. http://dx.doi.org/10.33225/jbse/18.17.765.

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This research reports on the effectiveness of Polya Problem-Solving and Target-Task collaborative learning approaches in electricity amongst high school physics students. It also includes a gender focus. It was an experimental research with a pre-test post-test control group design. The experimental groups were exposed to Polya Problem-Solving approach and Target-Task collaborative learning approach while the control group were exposed to conventional teaching. A total of 180 students were selected and divided equally into three groups, 60 (male adolescent and female adolescent) each. The students were initially pre-tested, followed by teaching and learning in electricity using the treatments, and finally they were post-tested using the Performance Test in Current Electricity (PTCE). Data were analyzed quantitatively with descriptive statistics and ANCOVA, and the research hypotheses were tested at .05 alpha level of significance. The research confirmed that both the treatments, Polya Problem-Solving and Target-Task collaborative learning approaches enhanced the performance of the students based on gender and scoring abilities compared with the conventional teaching. Keywords: collaborative learning, conventional teaching, gender, performance, physics students’, Polya problem-solving, target-task.

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Siswanto, Siswanto, e Yulaikah Yulaikah. "Implementation of Cognitive Learning Theory in Polya Learning to Improve Mathematical Problem Solving Ability". Jurnal Analisa 9, n. 1 (30 giugno 2023): 48–58. http://dx.doi.org/10.15575/ja.v9i1.25026.

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Penelitian ini bertujuan untuk menguji efektivitas penerapan teori pembelajaran kognitif dalam pembelajaran Polya terhadap kemampuan pemecahan masalah matematika siswa di salah satu SMA di Magelang menggunakan desain penelitian eksperimen. Subjek penelitian adalah siswa kelas 10 yang dibagi menjadi kelompok eksperimen dan kelompok kontrol. Kelompok eksperimen menerima pembelajaran Polya dengan penerapan teori pembelajaran kognitif, sementara kelompok kontrol menerima pembelajaran Polya tanpa penerapan teori pembelajaran kognitif. Data dikumpulkan melalui tes dan observasi kelas. Hasil analisis data menggunakan software SPSS dengan teknik analisis statistik ANOVA menunjukkan bahwa terdapat perbedaan signifikan antara kelompok. Selain itu, hasil analisis menunjukkan bahwa terdapat peningkatan yang signifikan dalam kemampuan pemecahan masalah matematika siswa pada kelompok eksperimen setelah intervensi. Hasil analisis observasi kelas menunjukkan adanya peningkatan interaksi antara siswa dan guru serta penggunaan strategi metakognitif oleh siswa dalam kelompok eksperimen. Berdasarkan hasil penelitian, dapat disimpulkan bahwa penerapan teori pembelajaran kognitif dalam pembelajaran Polya secara signifikan meningkatkan kemampuan pemecahan masalah matematika siswa di SMA di Magelang. Oleh karena itu, penelitian ini merekomendasikan penerapan teori pembelajaran kognitif dalam pembelajaran Polya sebagai salah satu alternatif untuk meningkatkan kemampuan pemecahan masalah matematika siswa di SMA di Magelang. This study aims to test the effectiveness of the application of cognitive learning theory in Polya learning on the mathematical problem-solving ability of students in one of the high schools in Magelang using an experimental research design. The subjects of the study were 10th-grade students who were divided into an experimental group and a control group. Data were collected through classroom tests and observations. The results of data analysis using SPSS software with ANOVA statistical analysis techniques showed that there were significant differences between groups. In addition, the results of the analysis showed that there was a significant improvement in students' mathematical problem-solving abilities in the experimental group after the intervention. Based on the results of the study, it can be concluded that the application of cognitive learning theory in Polya learning significantly improves the mathematical problem-solving ability of students in high school in Magelang. Therefore, this study recommends the application of cognitive learning theory in Polya learning as an alternative to improve students' mathematical problem-solving skills in high school in Magelang.

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TAKENAKA, S., M. MANABE, M. YOKOYAMA, M. NISHI, J. TANAKA e H. KONDO. "ChemInform Abstract: Specific Binding to PolyA of a Naphthalene Diimide Carrying Thymine Groups." ChemInform 27, n. 24 (5 agosto 2010): no. http://dx.doi.org/10.1002/chin.199624155.

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Raja Rao, B., e K. G. Janardan. "The generalized Markov-Polya probability model for ascertainment of groups of individuals in social processes". Mathematical Biosciences 73, n. 1 (marzo 1985): 33–50. http://dx.doi.org/10.1016/0025-5564(85)90074-4.

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Cahyadi, Muhammad Rizki, Bhaskoro Prasetyo Adi Maryanto, Mohammad Syaifuddin e Rani Darmayanti. "Development of Essay Test Assessment Rubric for Polya Theory-Based Mathematical Problem-Solving". JNPM (Jurnal Nasional Pendidikan Matematika) 7, n. 1 (31 marzo 2023): 167. http://dx.doi.org/10.33603/jnpm.v7i1.7724.

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Abstract. Assessment is an important part of the learning process. However, assessment is often carried out subjectively by the examiner, especially in essay tests. The scoring rubric is one of the solutions to minimize the subjectivity of the assessment to produce more objective and consistent grades. Therefore, it is necessary to develop an essay test assessment rubric. This study aims to produce a rubric for evaluating essay tests for mathematical problem-solving abilities based on Polya's theory. The method for developing an assessment rubric uses the Plomp model which consists of three phases, namely the initial research phase, the prototype phase, and the assessment phase. The results of the validity test by experts obtained a score of 3.40 on a scale of 1-4. The rubric of the validation results was then implicated in the assessment of the essay test given to 30 junior high school students. The implication of the rubric is as well as an empirical test of the effectiveness of the rubric. The empirical test results using three groups of raters obtained a correlation coefficient of 0.9290. Based on the results of validity tests and empirical tests, it can be concluded that the rubric for assessing essay tests for mathematical problem-solving abilities based on Polya theory is valid and feasible.Keywords: Mathematical Problem Solving, Polya, Rubric Assesment, Essay Test.

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LIANG, XUN. "COMPLEXITY OF ERROR HYPERSURFACES IN MULTILAYER PERCEPTRONS". International Journal of Neural Systems 14, n. 03 (giugno 2004): 189–200. http://dx.doi.org/10.1142/s0129065704001978.

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Error hypersurfaces are very valuable to study because of their unique status in multilayer perceptron research. Given the architecture of a multilayer perceptron, if the pattern sets are different, so are the respective error hypersurfaces in the multilayer perceptron. Using the theory of groups and Polya Theorem, this paper constructs classes of congruent pattern sets and classes of congruent error hypersurfaces, and proves that the number of classes of congruent pattern sets is equal to the number of congruent error hypersurfaces. Calculation results lead to much fewer classes of congruent error hypersurfaces than the total error hypersurfaces, and show that as the input dimension N increases, the former number increases at a much lower rate than the latter number, thus simplifying the understanding of the complexity of classes of error hypersurfaces.

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Meilantifa, Meilantifa, e Endrayana Putut Laksminto Emanuel. "Commognitive Mahasiswa Dalam Menyelesaikan Soal Kontekstual Pemodelan Matematika". Briliant: Jurnal Riset dan Konseptual 9, n. 2 (30 maggio 2024): 299–305. http://dx.doi.org/10.28926/briliant.v9i2.1683.

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This research aims to describe students' cognitive abilities in mathematical modeling material. The methods used in this research are preparation, data collection, transcription and analysis. A total of nine students who were grouped into three groups were given mathematics problem sheets, containing contextual story problems consisting of one number regarding mathematical modeling. A student representing his group was selected as a research subject based on Polya indicators and was interviewed in a semi-structured and in-depth manner to dig up further information and then analyzed cognitively. The research results show that the research subjects can solve mathematical problems well. The subject can communicate ordinary sentences well into mathematical models. The components of words use, visual mediators, narratives, and routines show that students' cognitive ability in solving mathematical contextual problems is very good in mathematical modeling material.

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Alam, Sangga Patih, Sripatmi Sripatmi, Baidowi Baidowi e Amrullah Amrullah. "Kemampuan Pemecahan Masalah High Order Thinking Skill Siswa Kelas VIII SMP Negeri 6 Mataram Tahun Pelajaran 2020/2021 Ditinjau Dari Prestasi Belajar Siswa". Griya Journal of Mathematics Education and Application 2, n. 1 (31 marzo 2022): 275–84. http://dx.doi.org/10.29303/griya.v2i1.142.

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The research was aim to describe the ability of class VIII SMP Negeri 6 students 2020/2021 academic year in solving problems on HOTS questions nased on student learning achievement. This research is classified as qualitative-descriptive research. The subjects of this research were 37 students of class VIII D and VIII E of SMP Negeri 6 Mataram on the 2020/2021 academic year, the subjects were grouped according to the results of a high, medium, and low mathematics learning achievement by using results of the odd semester test for the 2020/2021 academic year as the reference. Data collection techniques used is test techniques and interview techniques. The test technique is 2 HOTS solving ability questions for number pattern material. The interview technique was used to obtain detailed information about the students' views on problem-solving steps on the questions. The results of HOTS problem-solving ability test were analyzed according to Polya stages of problem-solving abilities. Based on the results of data analysis of groups with high learning achievement students, 75% of students met the indicators of the stages of understanding problems and planning solutions, 100% of students fulfilled the stages of completing settlements, and no students were able to meet the stages of re-examination. From the group of students with moderate learning achievement, 70.6% of students were able to meet the stages of understanding the problem, 58.8% of students met the stages of planning a solution, and 35.3% of students fulfilled the stages of solving problems and checking back. From the group of students with low learning achievement, only 6.3% of students were able to fulfill the stages of understanding the problem, the rest were unable to fulfill the four stages of problem-solving Polya.

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Jahudin, Janet, Nyet Moi Siew e Mad Noor Madjapuni. "THE EFFECT OF THE DIGITAL BAR MODEL WITH POLYA PROBLEM SOLVING INTEGRATION METHOD ON THE ALGEBRA THINKING SKILLS OF FORM FOUR STUDENTS". International Journal of Education, Psychology and Counseling 9, n. 55 (10 settembre 2024): 22–43. https://doi.org/10.35631/ijepc.955002.

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In general, there is still a lack of empirical studies to support the positive effects of digital technology integration methods in problem solving (PS), although there are assertions that these methods improve students' algebraic thinking skills. Therefore, the objective of this study is to evaluate whether the method of integrating the digital bar model in Polya’s problem solving (PPSBM) can improve the skills of Form One students to think algebraically. Ralston's framework, which includes Generalized Arithmetic, Functions, and Modeling in the topic of Linear Equations, serves as the basis for the assessment of algebraic thinking skills. A quasi-experimental design of pre-test and post-test control groups was used. A total of 90 Form One students, aged twelve to thirteen years, from a secondary school in Tambunan, Sabah, Malaysia, were involved as a sample. Three teaching groups were formed: PPSBM (n = 30), Bar Model (MB) (n = 30), and Conventional Problem Solving (CPS) (n = 30). Both pre- and post-algebra thinking tests were administered to students. The post-test was analyzed using MANCOVA with the students' pre-test results acting as covariates. The results showed that students in the PPSBM group performed better in Generalized Arithmetic, Functions and Modeling than students in the MB group, which in turn outperformed students in the CPS group. These results show that the method of integrating the digital bar model in Polya’s problem solving is a successful method to improve the algebraic thinking skills of Form One students.

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Rosikhoh, Dewi, Adin Lazuardy Firdiansyah e Riskiyatul Hasanah. "Investigasi Pemecahan Masalah Matematika Berdasarkan Kategori Adversity Quotient pada Siswa Kelas XII". Jambura Journal of Mathematics Education 4, n. 2 (28 novembre 2023): 119–30. http://dx.doi.org/10.37905/jmathedu.v4i2.20302.

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In this manuscript, our research purpose was to describe how high school students solved geometry problems in terms of Adversity Quotient (AQ). This research was qualitative descriptive research. The subjects of this research were five students in grade 12 science divided into one climber student, one camper-climber student, two camper students, and one quitter-camper student. In this research, we used some instruments, namely the ARP questionnaire, problem-solving test questions, and interview guidelines. The qualitative data were analyzed by using the principles or steps of the Polya method in solving problems. The results showed that the climber and camper-climber students could understand the problem, make plans, carry out plans, and check back in solving the geometry problems. However, the camper-climber student in re-checking answers had not been equipped with other strategies or methods. The camper student could understand the problem, make plans, and carry out plans in solving the problems. It was just that the camper student making plans was not more complex than the plans made by the climber student. Meanwhile, the quitter-camper student could only understand the problem. Therefore, AQ categories of students could be used as one of the teacher considerations in forming groups when learning mathematics in class, especially in trying students’ problem-solving skills.

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Più fonti

Tesi sul tema "Polya groups"

Bovo, Eduardo. "O teorema de enumeração de Polya, generalizações e aplicações". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307501.

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Orientador: Jose Plinio de Oliveira Santos
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
Made available in DSpace on 2018-08-05T07:47:09Z (GMT). No. of bitstreams: 1 Bovo_Eduardo_M.pdf: 3427598 bytes, checksum: 757ebc9282f3c010e155c26ec46fb42a (MD5) Previous issue date: 2005
Resumo: Neste trabalho são desenvolvidos conceitos algébricos, analíticos e combinatórios que culminam no Teorema de Enumeração de Pólya; bem como são fornecidas muitas de suas aplicações em enumeração de padrões (grafos, colorações geométricas, tipos e permutações, etc). Tal teorema clássico, que tem suas bases em Teoria dos Grupos, utiliza fundamentalmente o conceito de funções geradoras, o que permite grande generalidade e computabilidade de resultados. Finalmente são apresentadas algumas generalizações do resultado principal, aplicações destas e também uma importante interpretação probabilística
Abstract: In this dissertation we present algebraic, analytic and combinatorial results that are used to prove Polya's Enumeration Theorem. Applications to counting patterns (graphs, colourings, permutations, etc.) are given. This classical Theorem has its foundations on the theory of groups and uses, mainly, the concept of generating functions which allows great generality and computability of results. At the end some generalizations of the main theorem are given including applications and, aiso, an important probabilistic interpretation
Mestrado
Combinatoria Enumerativa
Mestre em Matemática Aplicada

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Emmelin, Etienne. "Grοupes de classes et de Ροlya d'extensiοns abéliennes". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMC241.

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Pour des extensions galoisiennes K/Q, le groupe de Pólya de K est un sous-groupedu groupe de classes d’idéaux de K engendré par les idéaux ambiges. On démontredans cette thèse l’existence d’une infinité d’extensions abéliennes K/Q, dont le groupede Pólya est isomorphe à un groupe abélien fini G, prescrit. Pour cela on se ramèneau cas des l-extensions cycliques et l’on utilise le théorème de structure des groupesabéliens finis. De plus, on étudie le comportement asymptotique du groupe de classesrelatif d’extensions CM abéliennes K/Q, défini comme étant le quotient du groupede classes Cl(K), par le groupe de Pólya Po(K) et l’on montre qu’il n’existe qu’unnombre fini de tels corps dont le groupe de classes relatif est trivial. Enfin, on démontrel’existence d’une infinité de corps quadratiques successifs en caractéristique strictementpositive, dont le nombre de classes est divisible par un nombre premier, en montrantun analogue du théorème de Siegel pour les corps de fonctions
For Galois extensions K/Q, the Pólya group of K is a subgroup of the ideal classgroup of K generated by ambigous ideals. In this thesis, we prove the existence of infinitlymany abelian extensions K/Q, such that the Pólya group of K is isomorphic to aprescribed finite abelian group G. For this, we study the case of cyclic l-extensions andwe show the existence using the theorem of finite abelian group structure. In addition,we study the asymptotic behavior of the relative class group of abelian CM extensionsK/Q, defined as the quotient of the class group Cl(K) by the Pólya group Po(K) andwe show that there exists a finite number of such fields whose relative class group istrivial. Finally, we prove the existence of infinitely many successive quadratic field inpositive caracteristic, whose class number is divisible by a prime number, by showingan analogous of Siegel’s theorem for function fields

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Brough, Tara Rose. "Groups with poly-context-free word problem". Thesis, University of Warwick, 2010. http://wrap.warwick.ac.uk/35716/.

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We call a language poly-context-free if it is an intersection of finitely many contextfree languages. In this thesis, we consider the class of groups with poly-context-free word problem. This is a generalisation of the groups with context-free word problem, which have been shown by Muller and Schupp [17, 3] to be precisely the finitely generated virtually free groups. We show that any group which is virtually a finitely generated subgroup of a direct product of finitely many free groups has poly-context-free word problem, and conjecture that the converse also holds. We prove our conjecture for several classes of soluble groups, including the metabelian groups and torsion-free soluble groups, and present progress towards resolving the conjecture for soluble groups in general. Some results in the thesis may be of independent interest in formal language theory or group theory. In Chapter 2 we develop some tools for proving a language not to be poly-context-free, and in Chapter 5 we prove that every finitely generated soluble group which is not virtually abelian has a subgroup of one of a small number of types.

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MORESCHINI, LORENZO. "Poly-free constructions for some Artin groups". Doctoral thesis, Università degli studi di Pavia, 2019. http://hdl.handle.net/11571/1292066.

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Artin-Tits groups have fruitfully been studied since the thirties when Emil Artin introduced the family of braid groups in the context of knot theory. The precise definition of the whole family of Artin-Tits groups is due to Jacques Tits in the seventies who introduced them as extensions of Coxeter groups. Although their definition is purely algebraic and relies on certain combinatorial data encoded in a so called "Coxeter graph", their study is not limited to their own field, but connections with other branch of mathematics has been discovered such as geometric group theory and algebraic topology. Since the definition of Artin-Tits groups is given by means of Coxeter graphs, it's quite natural to wonder whether there exists any connection between the structure of the combinatorial data that is written in the graph and the algebraic properties of the associated group. Not surprisingly, this is sometimes the case and a number of results we present in this thesis state hypotheses on the structure of the Coxeter graph in order to infer algebraic information regarding the Artin-Tits group associated to it. However, the "slightest variation" in the structure of the graph may change a lot the properties of the related Artin-Tits group. This situation has the consequence that many general questions about these groups have been answered only for some more or less extended families using tools specifically developed for that cases. E.g., we do not know if all Artin-Tits groups are torsion free and proofs are known only for some of them. In particular, in our thesis we want to study poly-freeness, a strong structural property of groups that in turn implies an affirmative answer to questions like torsion-freeness, orderability and others. We achieve that the only poly-free Artin-Tits groups of finite type are those of type I_2(n) (n >= 3), A_3, B_3, B_4 and D_4 (with the only possible exception of F_4 which remains unknown at the moment). Moreover, we prove that all Artin-Tits groups whose associated graph is a tree or a forest are poly-free and in the last part we give an affirmative result about poly-freeness of Artin-Tits groups built starting from graphs that may be "more connected" than just a tree or a forest and that we hope to be able to further generalise in the future.
Artin-Tits groups have fruitfully been studied since the thirties when Emil Artin introduced the family of braid groups in the context of knot theory. The precise definition of the whole family of Artin-Tits groups is due to Jacques Tits in the seventies who introduced them as extensions of Coxeter groups. Although their definition is purely algebraic and relies on certain combinatorial data encoded in a so called "Coxeter graph", their study is not limited to their own field, but connections with other branch of mathematics has been discovered such as geometric group theory and algebraic topology. Since the definition of Artin-Tits groups is given by means of Coxeter graphs, it's quite natural to wonder whether there exists any connection between the structure of the combinatorial data that is written in the graph and the algebraic properties of the associated group. Not surprisingly, this is sometimes the case and a number of results we present in this thesis state hypotheses on the structure of the Coxeter graph in order to infer algebraic information regarding the Artin-Tits group associated to it. However, the "slightest variation" in the structure of the graph may change a lot the properties of the related Artin-Tits group. This situation has the consequence that many general questions about these groups have been answered only for some more or less extended families using tools specifically developed for that cases. E.g., we do not know if all Artin-Tits groups are torsion free and proofs are known only for some of them. In particular, in our thesis we want to study poly-freeness, a strong structural property of groups that in turn implies an affirmative answer to questions like torsion-freeness, orderability and others. We achieve that the only poly-free Artin-Tits groups of finite type are those of type I_2(n) (n >= 3), A_3, B_3, B_4 and D_4 (with the only possible exception of F_4 which remains unknown at the moment). Moreover, we prove that all Artin-Tits groups whose associated graph is a tree or a forest are poly-free and in the last part we give an affirmative result about poly-freeness of Artin-Tits groups built starting from graphs that may be "more connected" than just a tree or a forest and that we hope to be able to further generalise in the future.

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Leriche, Amandine. "Groupes, corps et extensions de Polya : une question de capitulation". Phd thesis, Université de Picardie Jules Verne, 2010. http://tel.archives-ouvertes.fr/tel-00612597.

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Dans cette thèse, nous nous intéressons à l'ensemble $Int\left(\mathcal O _K \right)$ des polynômes à valeurs entières sur l'anneau $\mathcal{O}_K$ des entiers d'un corps de nombres $K$. Selon Pólya, une base $\left(f_{n}\right)_{n\in \mathbb{N}}$ du $\mathcal O _K$-module $Int\left(\mathcal O _K \right)$ est dite régulière si pour tout $n \in \mathbb{N}$, $\deg(f_{n})=n$. Un corps $K$ tel que $ Int \left(\mathcal{O}_K \right)$ possède une base régulière est dit de Pólya et le groupe de Pólya d'un corps de nombres $K$ est un sous-groupe du groupe de classes de $K$ qui peut être considéré comme une mesure de l'écart pour un corps au fait d'être de Pólya. Nous étudions le groupe de Pólya d'un compositum $L= K_1 K_2$ de corps de nombres galoisiens et établissons des liens avec la ramification des nombres premiers dans chacune des extensions $K_1 /\mathbb{Q}$ et $K_2 /\mathbb{Q}$. Nous appliquons ces résultats aux corps de nombres de petit degré afin d'élargir la famille des corps de Pólya quadratiques déjà caractérisés. Par ailleurs, une condition pour qu'un corps de nombres $K$ soit de Pólya est que tous les produits d'idéaux de $K$ de même norme soient principaux. Par analogie avec le problème classique du plongement, on peut se poser la question suivante : tout corps de nombres $K$ peut-il être plongé dans un corps de Pólya? Nous donnons une réponse positive à cette question : pour tout corps $K$, le corps de classes de Hilbert $H_K$ de $K$ est un corps de Pólya . Toujours par analogie avec le problème de plongement où l'on sait que les idéaux de $\mathcal{O}_K$ deviennent principaux dans $\mathcal{O}_{H_K}$, on peut définir la notion d'extension de Pólya d'un corps $K$ : il s'agit de corps $L$ contenant $K$ dans lesquels le groupe de Pólya de $K$ devient trivial par extensions des idéaux, ce sont aussi des corps $L$ tels que le $\mathcal O _L$-module engendré par $Int\left(\mathcal O _K \right)$ possède une base régulière. Outre $H_K$ dans le cas général, dans le cas où $K$ est une extension abélienne, la capitulation des idéaux ambiges de $K$ montre que le corps de genre de $K$ en est une extension de Pólya. Ceci nous amène à des questions de minimalité et d'unicité concernant les corps et extensions de Pólya.

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Cameron, Donald King. "Some reactions of unsaturated ring systems containing sulphonyl groups". Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/10859.

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Green, Shawn Jeffrey. "Extensions of the Power Group Enumeration Theorem". BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7526.

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The goal of this paper is to develop extensions of Polya enumeration methods which count orbits of functions. De Bruijn, Harary, and Palmer all worked on this problem and created generalizations which involve permuting the codomain and domain of functions simultaneously. We cover their results and specifically extend them to the case where the group of permutations need not be a direct product of groups. In this situation, we develop a way of breaking the orbits into subclasses based on a characteristic of the functions involved. Additionally, we develop a formula for the number of orbits made up of bijective functions. As a final extension, we also expand the set we are acting on to be the set of all relations between finite sets. Then we show how to count the orbits of relations.

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Abdellatif, Mohamed Moustafa. "Poly(arylene ether)s with Truly Pendant Benzene Sulfonic Acid Groups". Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1222544981.

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de, Santiago Rolando. "Structural results for von Neumann algebras of poly-hyperbolic groups". Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5745.

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This work is a compilation of structural results for the von Neumann algebras of poly-hyperbolic groups established in a series of works done jointly with I. Chifan and T. Sinclair; and S. Pant. These works provide a wide range of circumstances where the product structure, a discrete structural property, can be recovered from the von Neumann algebra (a continuous object). The primary result of Chifan, Sinclair and myself is as follows: if Γ = Γ1 × · · · × Γn is a product of non-elementary hyperbolic icc groups and Λ is a group such that L(Γ)=L(Λ), then Λ decomposes as an n-fold product of infinite groups. This provides a group-level strengthening of the unique prime decomposition of Ozawa and Popa by eliminating any assumption on the target group Λ. The methods necessary to establish this result provide a malleable procedure which allows one to rebuild the product of a group from the algebra itself. Modifying the techniques found in the previous work, Pant and I are able to demonstrate that the class of poly-groups exhibit a similar phenomenon. Specifically, if Γ is a poly-hyperbolic group whose corresponding algebra is non-prime, then the group must necessarily decompose as a product of infinite groups.

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Formosa, Joseph S. "Thermal degradation of polymer blends containing the poly (hydroxy, ether of bisphenol-A) /". Online version of thesis, 1987. http://hdl.handle.net/1850/10289.

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Libri sul tema "Polya groups"

author, Gabolaev Z. P., e Severo-Osetinskiĭ institut gumanitarnykh i sot︠s︡ialʹnykh issledovaniĭ imeni V.I. Abaeva, a cura di. Imennoĭ spisok tuzemt︠s︡am muzhskogo pola Osetinskogo okruga, sostavlennyĭ komissieĭ po opredelenii︠u︡ prav lichnykh i pozemelʹnykh togo okruga Ii︠u︡li︠a︡ 30 dni︠a︡ 1863 goda. Vladikavkaz: Severo-Osetinskiĭ institut gumanitarnykh i sot︠s︡ialʹnykh issledovaniĭ im. V.I. Abaeva VNT︠S︡ RAN, 2021.

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Gallery, Polka Art. Tiger! Tiger!: A group exhibition of new art works to support saving the tigers 25th--26th April 2011 at Aman New Delhi, 28th April--30th May 2011 at the Polka Art Gallery. New Delhi: Polka Art Gallery, 2011.

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Hubbard, K. Lise. The study of poly (Divinylbenzene-co-ethylvinylbenzene) and modifications to the pendant vinylbenzene groups. Montréal, Qué, 1997.

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Chestakova, Alexandra. Interfacial equilibrium and dynamic properties of telechelic poly(ethylene oxide) end-capped by alkyl groups. 2003, 2003.

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Version, New International. NIV Journalling Mint Polka Dot Cloth Bible. Hodder & Stoughton, 2013.

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Panigrahi, Muktikanta, e Arpan Kumar Nayak. Polyaniline based Composite for Gas Sensors. IOR PRESS, 2021. http://dx.doi.org/10.34256/ioriip212.

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In this research work, we have demonstrated the synthesis, spectroscopic characteristics, thermal behaviour and DC conductivity of a few nanostructured composites, substituted conducting polymers (ICPs) and composites of ICPs. The physical properties of aforementioned composites are significantly changed by the doping with HCl, H2SO4, HNO3, H3PO4, or acrylic acid. The charge transport properties of these polymeric materials have been studied in detail because of their potential application in gas sensors. In the current work, varieties of conducting polymer based materials such as PANI-ES/Cloisite 20A nanostructured composite, acrylic acid (AA) doped PANI polymer, N-substituted conducting polyaniline polymer, DL−PLA/PANI-ES composites, poly methyl methacrylate (PMMA) based polyaniline composite, and inorganic acid doped polyaniline are sucessfuly synthesized using aniline/aniline hydrochloride as precursors in acidic medium. Particularly, AA based synthesised PANI polymer was found with higher solubility The spectroscopic, thermal stability, enthalpy of fusion, room temperature DC conductivity and temperature dependent DC conductivity measurements with and without magnetic was carried out with as-synthesized materials. The FTR/ATR−FTIR spectra indicated the presence of different functional groups in the as-prepared composite materials. The UV−Visible absorption spectroscopic analysis showed the presence of polaron band suggesting PANI-ES form. The Room temperature DC conductivity, temperature variation DC conductivity (in presence and absence of magnetic field), and magnetoresistance (MR) of as-prepared conducting polyaniline based were analysed. The highest room temperature DC conductivity value was obtained from H2SO4 doped based composite materials and all prepared conductive composites were followed ohms law. The low temperature DC conductivity was carried out in order to study the semiconducting nature of prepared materials. The Mott type VRH model was found to be well fitted the conductivity data and described the density of states at the Fermi level which is constant in this temperature range. From MR plots, a negative MR was observed, which described the quantum interference effect on hopping conduction. We discuss different gas analytes i.e., NO2, LPG, H2, NH3, CH4, and CO of conducting polymer based materials.

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Capitoli di libri sul tema "Polya groups"

Yekta, Ahmad, Thierry Nivaggioli, Sabeshan Kanagalingam, Bai Xu, Zahra Masoumi e Mitchell A. Winnik. "Urethane-Coupled Poly(ethylene glycol) Polymers Containing Hydrophobic End Groups". In Advances in Chemistry, 363–76. Washington, DC: American Chemical Society, 1996. http://dx.doi.org/10.1021/ba-1996-0248.ch019.

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Fontana, Francesco, e Giampaolo Campana. "Per- and Polyfluoroalkyl Substances: An Environmental Challenge". In Lecture Notes in Mechanical Engineering, 793–800. Cham: Springer Nature Switzerland, 2025. https://doi.org/10.1007/978-3-031-77429-4_88.

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AbstractPer- and poly-fluoroalkyl substances are a group of synthetic aliphatic compounds containing one or more perfluoroalkyl moieties (CnF2n + 1-). Due to their unique surface-active properties and high chemical and thermal stability, they are used in various consumer products such as cosmetics, food packaging, furnishings, and textiles. Their use dates back to the 1940s. Despite their peculiar performances, recent scientific works investigate their sustainability and safety deriving from environmental ubiquity, persistence and bioaccumulation. Indeed, these chemicals are not metabolized in animals and are eliminated mainly through the kidneys, with a low excretion capacity in the case of humans. Many studies conducted worldwide have reported significant serum levels of per- and poly-fluoroalkyl substances in most of the general population, associating them with several health conditions, including hepatoxicity, dyslipidaemia, and endocrine and immunotoxicity outcomes. Besides, new sources of emissions due to degradation phenomena are continuously identified. Consequently, long-chain per- and poly-fluoroalkyl substances have triggered supervising actions and restrictions that fostered research about possible alternatives. This article aims to screen current European scientific investigations conducted to evaluate the impact of these chemicals on the environment and human health, focusing on food packaging and textile production. Due to the paper’s length limitation, not all the scientific literature is described because of the need to leave space to discuss possible substitutes. Relevant studies are reported about implementing sustainability and safety/hazard assessment for per- and poly-fluoroalkyl substances. Eventually, the need to develop new and specific analysis methods is discussed.

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Wallach, Joshua A., e Samuel J. Huang. "Methacrylic Group Functionalized Poly(lactic acid) Macromonomers from Chemical Recycling of Poly(lactic acid)". In ACS Symposium Series, 281–92. Washington, DC: American Chemical Society, 2001. http://dx.doi.org/10.1021/bk-2000-0764.ch018.

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Taguchi, Yoshihiro, Hiroshi Uyama, Shiro Kobayashi e Katsuhisa Osada. "Synthesis and Properties of Poly(Aryl Ether Ketone) Possessing Crosslinking Groups". In Macromolecular Engineering, 319–28. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1905-8_25.

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Andronie, A., I. Stamatin, S. Iordache, Ana Cucu, S. Stamatin e S. Antohe. "Glycerine Treatment of Poly-Perfluorosulphonic Acid Membrane Modified by Sulfonamide Groups". In NATO Science for Peace and Security Series A: Chemistry and Biology, 227–30. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2488-4_24.

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Hatakeyama, Kazuyuki, Yasuo Nemoto, Kunihiro Ueda e Osamu Hayaishi. "Poly(ADP-Ribose) Glycohydrolase and ADP-Ribosyl Group Turnover". In ADP-Ribose Transfer Reactions, 47–52. New York, NY: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4615-8507-7_8.

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Tokuda, Shingo, Akiko Obata e Toshihiro Kasuga. "Preparation of Calcium Carbonate / Poly(Lactic Acid) Composite Membranes Containing Mercapto Groups". In Key Engineering Materials, 487–90. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-422-7.487.

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Wohlfarth, Ch. "Second virial coefficient of poly(methyl methacrylate) (with two NH2-end groups)". In Polymer Solutions, 976. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-02890-8_607.

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Rhee, Sang Hoon, Sun Ja Lee, Young Mi Kang, Yong Keun Lee, Bum Soon Lim e Seung Jin Lee. "Synthesis of Poly(ε-Caprolactone)-Organosiloxane Hybrid Containing Amine Group". In Key Engineering Materials, 1277–80. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-422-7.1277.

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Neelov, I., S. Niemelä, F. Sundholm e M. Skrifvars. "Molecular Dynamics Simulation of Unsaturated Polyesters Modified by Poly(Ethylene Glycol) end Groups". In Progress and Trends in Rheology V, 340–41. Heidelberg: Steinkopff, 1998. http://dx.doi.org/10.1007/978-3-642-51062-5_161.

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Atti di convegni sul tema "Polya groups"

Wang, Jiahao, e Takahiro Kozawa. "Dissolution dynamics of poly(4-hydroxystyrene) partially protected with t-butoxycarbonyl group in alkyl-trimethyl-ammonium hydroxide aqueous developers". In International Conference on Extreme Ultraviolet Lithography 2024, a cura di Joern-Holger Franke, Kurt G. Ronse, Paolo A. Gargini, Patrick P. Naulleau e Toshiro Itani, 51. SPIE, 2024. http://dx.doi.org/10.1117/12.3032260.

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Natansohn, A., P. Rochon, J. Mao e S. Xie. "Optical Storage in Polymers Containing Azo Groups without Electron-Donor - Electron Acceptor Substituents: Poly[4-(2-methacryloyloxy)ethyl-azobenzene]". In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/otfa.1993.wd.25.

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Some degree of supramolecular organization can be induced in amorphous polymers containing azobenzene groups by means of polarized light. This phenomenon has been known for about a decade and the relevant literature has been reviewed in one of our recent publications1. This induced preferred orientation of the azobenzene groups can be monitored by a significant change in the refractive index of the polymer film and can thus be usea as an information storage mechanism. Circularly polarized light restores the natural disorder of the azobenzene orientations, enabling erasure of the stored information1-5. This phenomenon was first noticed on polymers doped with substituted azobenzenes and was intensively studied on liquid crystalline polymers containing substituted azobenzenes as the mesogenic group. Probably by chance - due to the availability of various azo dyes and to the ease of synthesis - almost all examples previously studied in the literature had electron-donor and electron-acceptor substituents on the azobenzene groups. Their presence conferred another important dimension to this type of supramolecular organization: starting with a polarizable group one could induce second order nonlinear susceptibility in the material, thus opening the possibility of applications in photonics.

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Lin, Hsiu-Li, Chih-Ren Hu, Po-Hao Su, Yu-Cheng Chou e Che-Yu Lin. "Proton Exchange Membranes Based on Blends of Poly(Benzimidazole) and Butylsulfonated Poly(Beznimidazole) for High Temperature PEMFC". In ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2010. http://dx.doi.org/10.1115/fuelcell2010-33031.

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Phosphoric acid doped poly(benzimidazole) (PBI) is one of excellent candidates of proton exchange membranes for high temperature (150–180°C) proton exchange membrane fuel cells (PEMFCs). However, the strong inter-polymer hydrogen bonds cause low elongation and brittleness of PBI membranes. In this work, we synthesize poly(benzimidazole) (PBI) and butylsulfonated poly(benzimidazole) (PBI-BS), in which around 22 mole% of imidazole –NH groups of PBI are grafted with sulfonated butyl groups. We show the elongation, phosphoric acid doping level, and proton conductivity of PBI can be improved by blending ∼ 20 wt% of PBI-BS in the PBI membrane, and the membrane electrode assembly prepared from PBI/PBI-BS (8/2 by wt) blend membrane has a better PEMFC performance at 140°C ∼ 180°C than that prepared from PBI membrane. It is believed that the crosslink interactions of imidazole -NH and -N=C-groups with side chain –C4H8−SO3H groups of PBI-BS reduces the inter-PBI hydrogen bonds and increases the free volume of polymers, which leads to the enhancements of the membrane toughness and phosphoric acid doping level and the PEMFC performance.

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Basché, Th, S. Kummer, R. Kettner, J. Tittel e C. Bräuchle. "Single Molecule Spectroscopy of Novel Crystalline and Polymeric Systems". In Spectral Hole-Burning and Related Spectroscopies: Science and Applications. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/shbs.1994.wb3.

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Single molecule spectroscopy in solids at low temperature is a very rapidly growing field which due to the sensitivity of a single molecule to its truly local environment yields new insights in the structure and dynamics of crystalline and amorphous solids [1,2]. In the first years of SMS a lot of different experimental techniques have been applied to only a few well selected systems. These were the mixed crystalline system pentacene in p-terphenyl, and perylene and terrylene in poly(ethylene). Very recently, it was recognized by several groups that it is important to find new systems to demonstrate the more general applicability of this new and exciting spectroscopy. While there are several - well known - stringent requirements for any specific system to observe single molecule spectra with the fluorescence excitation technique, recent successful experiments proved that there is still a wide variety of systems where SMS can be pursued. Two new systems introduced lately were terrylene in the Shpol’skii matrix hexadecane [3] and Rhodamine 640 in (poly)ethylene [4]. In our group we investigated new crystalline as well as new polymeric systems.

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Su, Zhiqing, Hui Xu, Yingcheng Li, Hui Sun, Jun Jin, Bin Wang, Aiqing Ma, Xiujuan He e Ou Sha. "Research of Polymeric Surfactant as Multifunctional Monocomponent Oil Displacement Agent in EOR". In Middle East Oil, Gas and Geosciences Show. SPE, 2023. http://dx.doi.org/10.2118/213456-ms.

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Abstract SP (Surfactant-Polymer) flooding is one of the most common methods in Enhance Oil Recovery (EOR). However, chromatographic separation underground limits its efficiency due to the enormous difference in molecular size between polymer and surfactant. A single-component oil displacement agent, polymeric surfactant (PolyS), was studied to solve the chromatographic separation. Properties were investigated under the reservoir conditions, including viscosity, interfacial activity, injectivity, adsorption, and core flooding. With the increase of the active functional group content, the viscosity decreased, while the oil-water interfacial activity increased. The viscosity of PolyS was higher than 10mPa∙s, and interfacial tension (IFT) was lower than 3×10-2 mN/m at 2500 mg/L PolyS in the brine with a salinity of 66560 mg/L at 72°C. The middle phase emulsion was formed when mixing crude oil and PolyS solution, indicating that PolyS had better capability to emulsify crude oil than commercial polyacrylamide (PAM). Furthermore, the adsorption amount of PolyS on silica with diameter of 100-150 μm was 1.16 mg/m2. PolyS can be easily injected into sandpack with different permeabilities from 300 mD to 1000 mD. The oil displacement results showed that an improved oil recovery of 26.15% OOIP was achieved with an injection of 0.3 PV PolyS solution containing a 2.04 mol% active functional group, which had both low IFT and high viscosity. As a comparison, only 20% OOIP was obtained for commercial PAM.

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Zhou, Xue, Zhengyao Bai, Qianjie Lu, Ao Huang e Shenglan Fan. "Colorectal Polyp Segmentation Based on Group Convolution and Transformer". In 2021 China Automation Congress (CAC). IEEE, 2021. http://dx.doi.org/10.1109/cac53003.2021.9728295.

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Rusu, Stefan. "Establishing of the mono- and polyinvasion impact on some morpho-functional indices in wild boars". In Xth International Conference of Zoologists. Institute of Zoology, Republic of Moldova, 2021. http://dx.doi.org/10.53937/icz10.2021.44.

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In the paper is described the mono- and poly-invasions impact on some morpho-functional indices in wild boars. So, in result of the investigation of hematological indices in uninfested mono- and poly-parasitized wild boars, it was established that both the indices of hemoglobin content, of hematocrit, erythrocyte’s number, thrombosis time and ESR (erythrocyte sedimentation rate) vary and are more increased in the I group with uninfested wild boars compared to mono - and poly-parasitized ones. It has been established that at infested boars with S. papillosus from the I group, and in those infested with D. lanceolatum from the II group there is a decrease of hemostatic indices, but their maximum decrease is highlighted in the IV group with wild boars infested with Dicrocoelium lanceolatum, Strongyloides papillosus, Metastrongylus elongatus and Eimeria debliecki. This decrease is due to eliminated exotoxins by parasites, which contain anticoagulants and hemolyzers and which neutralize the fibrinogen, thrombin, Ca+ ions and vitamin K properties from the body.

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Gao, Xifeng, Kui Wu e Zherong Pan. "Low-poly Mesh Generation for Building Models". In SIGGRAPH '22: Special Interest Group on Computer Graphics and Interactive Techniques Conference. New York, NY, USA: ACM, 2022. http://dx.doi.org/10.1145/3528233.3530716.

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Zhang, Bengui, Shouhai Zhang e Xigao Jian. "Poly (phthalazinone ether ketone) anion exchange membranes with pyridinium groups as ion exchange groups for vanadium redox flow battery". In 2013 International Conference on Materials for Renewable Energy and Environment (ICMREE). IEEE, 2013. http://dx.doi.org/10.1109/icmree.2013.6893720.

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Zhang, Mingwen, Haiying Xia e Yumei Tan. "GroupSeg: An Efficient Grouping Transformer Network for Polyp Segmentation". In 2023 IEEE International Conference on Bioinformatics and Biomedicine (BIBM). IEEE, 2023. http://dx.doi.org/10.1109/bibm58861.2023.10385401.

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Rapporti di organizzazioni sul tema "Polya groups"

Baker, Kenneth N., e Albert V. Fratini. Crystal Structures of Poly-Paraphenylene Oligomers Containing Pendant Phenyl Groups. Fort Belvoir, VA: Defense Technical Information Center, settembre 1989. http://dx.doi.org/10.21236/ada218158.

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Dr. Thieo Hogen-Esch. Complex formation of beta-cyclodextrin in aqueous media with poly(N,N-dimethylacrylamide)containing pendent perfluorooctanesulfonamido groups. Final Report, September 15, 1998 - September 14, 1999. Office of Scientific and Technical Information (OSTI), novembre 1999. http://dx.doi.org/10.2172/756725.

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Luft, Charles, Timothy Schutt e Manoj Shukla. Properties and mechanisms for PFAS adsorption to aqueous clay and humic soil components. Engineer Research and Development Center (U.S.), maggio 2024. http://dx.doi.org/10.21079/11681/48490.

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The proliferation of poly- and perfluorinated alkyl substances (PFASs) has resulted in global concerns over contamination and bioaccumulation. PFAS compounds tend to remain in the environment indefinitely, and research is needed to elucidate the ultimate fate of these molecules. We have investigated the model humic substance and model clay surfaces as a potential environmental sink for the adsorption and retention of three representative PFAS molecules with varying chain length and head groups. Utilizing molecular dynamics simulation, we quantify the ability of pyrophyllite and the humic substance to favorably adsorb these PFAS molecules from aqueous solution. We have observed that the hydrophobic nature of the pyrophyllite surface makes the material well suited for the sorption of medium- and long-tail PFAS moieties. Similarly, we find a preference for the formation of a monolayer on the surface for long-chain PFAS molecules at high concentration. Furthermore, we discussed trends in the adsorption mechanisms for the fate and transport of these compounds, as well as potential approaches for their environmental remediation.

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Tompson, Lisa, Apriel Jolliffe Simpson, Richard Wortley, Bridget O'Keeffe e Devon Polaschek. Understanding re-victimisation through an intersectional lens. The University of Waikato, 2024. https://doi.org/10.15663/tph91171.

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Policy efforts based on evidence about risk for re-victimisation both protect some of the most vulnerable people in society and have a good chance of reducing crime levels overall (Farrell and Pease, 1993; Grove et al., 2012; Pease et al., 2018). While research has established that the phenomenon of re-victimisation is ubiquitous, less is known about what makes some people more vulnerable to re-victimisation than others (Hamilton and Browne, 1998; Nazaretian and Fitch, 2021). Enhanced understanding of who these people are is thus crucial for developing contemporary victim-centred crime prevention policy. Victimology theories suggest that people at high risk of victimisation are typified by multiple overlapping and intersecting personal characteristics (e.g., gender, age, race/ethnicity, class, disability status, sexual identity), rather than forming homogeneous higher-order groups (e.g., delineated by a single personal characteristic; Shoham et al, 2010; Walklate, 2012). Accordingly, in this study we examined socio-demographic characteristics (e.g., gender, age, ethnicity, disability status, sexual identity) of people who were re-victimised, with an emphasis on intersectionality. That is, we focused on identifying where the co-occurrence of socio-demographic characteristics intensified risk of re-victimisation. We use re-victimisation as an umbrella term to cover: • Poly-victimisation (i.e., >1 victimisation for different types of crime), and • Repeat-victimisation (i.e., >1 victimisation for different types of crime) for 11 different crime types. We therefore analysed 12 different types of re-victimisation over five waves of the New Zealand Crime and Victims Survey (NZCVS) in the privacy- and security-protected environment of Statistics New Zealand’s Integrated Data Infrastructure (IDI) with Conjunctive Analysis of Case Configurations. This method enabled us to position groups (i.e., combinations of characteristics) as the unit of analysis and identify where intersecting characteristics were associated with high rates of re-victimisation and isolate when particular individual characteristics were especially noteworthy. This research makes four important contributions to the evidence base on victimisation. First, while re-victimisation experiences have been studied for a range of crime types internationally (see Farrell et al., 2005), this is the first research to do so for Aotearoa New Zealand. Second, it adds to the scant evidence base on poly-victimisation. Third, it corroborates the empirical findings from other countries that risk of re-victimisation increases cumulatively (Johnson et al., 1997), hence the need for policies and practices that get upstream of the problem and prevent re-victimisation at the earliest opportunity. Fourth, this research advances knowledge on how socio-demographic characteristics intersect to elevate risk of re-victimisation. The findings are relevant for policymakers developing victimisation prevention programmes across various organisations in Aotearoa New Zealand.

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Grumet, Rebecca, e Benjamin Raccah. Identification of Potyviral Domains Controlling Systemic Infection, Host Range and Aphid Transmission. United States Department of Agriculture, luglio 2000. http://dx.doi.org/10.32747/2000.7695842.bard.

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Potyviruses form one of the largest and most economically important groups of plant viruses. Individual potyviruses and their isolates vary in symptom expression, host range, and ability to overcome host resistance genes. Understanding factors influencing these biological characteristics is of agricultural importance for epidemiology and deployment of resistance strategies. Cucurbit crops are subject to severe losses by several potyviruses including the highly aggressive and variable zucchini yellow mosaic virus (ZYMV). In this project we sought to investigate protein domains in ZYMV that influence systemic infection and host range. Particular emphasis was on coat protein (CP), because of known functions in both cell to cell and long distance movement, and helper component-protease (HC-Pro), which has been implicated to play a role in symptom development and long distance movement. These two genes are also essential for aphid mediated transmission, and domains that influence disease development may also influence transmissibility. The objectives of the approved BARD project were to test roles of specific domains in the CP and HC-Pro by making sequence alterations or switches between different isolates and viruses, and testing for infectivity, host range, and aphid transmissibility. These objectives were largely achieved as described below. Finally, we also initiated new research to identify host factors interacting with potyviral proteins and demonstrated interaction between the ZYMV RNA dependent RNA polymerase and host poly-(A)-binding protein (Wang et al., in press). The focus of the CP studies (MSU) was to investigate the role of the highly variable amino terminus (NT) in host range determination and systemic infection. Hybrid ZYMV infectious clones were produced by substituting the CP-NT of ZYMV with either the CP-NT from watermelon mosaic virus (overlapping, but broader host range) or tobacco etch virus (TEV) (non- overlapping host range) (Grumet et al., 2000; Ullah ct al., in prep). Although both hybrid viruses initially established systemic infection, indicating that even the non-cucurbit adapted TEV CP-NT could facilitate long distance transport in cucurbits, after approximately 4-6, the plants inoculated with the TEV-CPNT hybrid exhibited a distinct recovery of reduced symptoms, virus titer, and virus specific protection against secondary infection. These results suggest that the plant recognizes the presence of the TEV CP-NT, which has not been adapted to infection of cucurbits, and initiates defense responses. The CP-NT also appears to play a role in naturally occurring resistance conferred by the zym locus in the cucumber line 'Dina-1'. Patterns of virus accumulation indicated that expression of resistance is developmentally controlled and is due to a block in virus movement. Switches between the core and NT domains of ZYMV-NAA (does not cause veinal chlorosis on 'Dina-1'), and ZYMV-Ct (causes veinal chlorosis), indicated that the resistance response likely involves interaction with the CP-NT (Ullah and Grumet, submitted). At the Volcani Center the main thrust was to identify domains in the HC-Pro that affect symptom expression or aphid transmissibility. From the data reported in the first and second year report and in the attached publications (Peng et al. 1998; Kadouri et al. 1998; Raccah et al. 2000: it was shown that: 1. The mutation from PTK to PAK resulted in milder symptoms of the virus on squash, 2. Two mutations, PAK and ATK, resulted in total loss of helper activity, 3. It was established for the first time that the PTK domain is involved in binding of the HC-Pro to the potyvirus particle, and 4. Some of these experiments required greater amount of HC-Pro, therefore a simpler and more efficient purification method was developed based on Ni2+ resin.

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