72 research outputs found
Polynomial homogeneous maps and their periods
We study the set of periods of the homogeneous polynomial maps f : Rn → Rn and f : Cn → Cn of degree m > 1. For these complex maps we also describe the number of invariant straight lines through the origin by fk for k = 1,2, . . ., and the dynamics of fk over them
Developing machine learning methods for classification and analysis of dichotic listening using neurophysiological data
東京電機大学202
Molybdenum alkylidene complexes : syntheses and applications to olefin metathesis reactions
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Vita.Includes bibliographical references.Chapter 1. Alkylimido Molybdenum Complexes: Synthesis, Characterization and Activity as Chiral Olefin Metathesis Catalysts. Molybdenum olefin metathesis catalysts that contain previously unexplored aliphatic 1- phenylcyclohexylimido (PhCyN) and 2-phenyl-2-adamantylimido (PhAdN) groups were prepared and shown to be efficient and selective in a variety of olefin metathesis reactions. Five catalysts, Mo(NR)(CHCMe2Ph)[(S)-Biphen], Mo(NR)(CHCMe2Ph)[(R)-Trip](THF) (R = 1- adamantyl, PhCy, PhAd; Biphen = 3,3'-di-tert-butyl-5,5',6,6'-tetramethyl-1,1'-biphenyl-2,2'- diolate; Trip = 3,3'-bis(2,4,6-triisopropylphenyl)- 1,1'-binaphthyl-2,2'-diolate) and Mo(NAd)(CHCMe2Ph)[(R)-Trip](THF) (Ad = I-adamantyl), were synthesized. Their catalytic activity and enantioselectivity in desymmetrization reactions such as ring-closing metathesis of amines and lactams and ring-opening/cross metathesis of a substituted norborneol with styrene were compared to the results obtained with the only known alkylimido catalyst, Mo(NAd)(CHCMe2Ph)[(S)-Biphen]. The new catalysts prove to be similar to Mo(NAd)(CHCMe2Ph)[(S)-Biphen] in the majority of the studied reactions, and the examined catalysts show overall improvement in activity and enantioselectivity compared to the traditional arylimido catalysts. Chapter 2. Synthesis of Molybdenum Imido Alkyl and Alkylidene Complexes from Molybdenum Imido Tetrachlorides. Several new Mo(NR)C14(THF) species (R = C6F5, 3,5-(CF3)2C6H3, Ad, CPh3, and 2,6-i- Pr2C6H3) were prepared via the treatment of MoC14(THF)2 with azides, and then alkylated with neopentyl reagents. Addition of Mo(NR)C14(THF) complexes in toluene to a cold solution of NpMgCl in ether gave Mo(NR)Np3Cl species (R = CFs5, 3,5-(CF3)2C6H3, Ad, Ph3C, and 2,6-i- Pr2C6H3 (Ar); Np = CH2-t-Bu) in poor (35 %) to modest (51 %) yields. Heating Mo(NAr)Np3C1 in C6D6 to 50 OC results in a-hydrogen abstraction to give neopentane and a molecule whose(cont.) Chapter 2. Synthesis of Molybdenum Imido Alkyl and Alkylidene Complexes from Molybdenum Imido Tetrachlorides. Several new Mo(NR)C14(THF) species (R = C6F5, 3,5-(CF3)2C6H3, Ad, CPh3, and 2,6-i- Pr2C6H3) were prepared via the treatment of MoC14(THF)2 with azides, and then alkylated with neopentyl reagents. Addition of Mo(NR)C14(THF) complexes in toluene to a cold solution of NpMgCl in ether gave Mo(NR)Np3Cl species (R = CFs5, 3,5-(CF3)2C6H3, Ad, Ph3C, and 2,6-i- Pr2C6H3 (Ar); Np = CH2-t-Bu) in poor (35 %) to modest (51 %) yields. Heating Mo(NAr)Np3C1 in C6D6 to 50 OC results in a-hydrogen abstraction to give neopentane and a molecule whose NMR spectra are consistent with it being Mo(NAr)(CH-t-Bu)NpCl; it decomposed bimolecularly upon attempted isolation. The other Mo(NR)Np3Cl species were found to be more stable than Mo(NAr)Np3C1, but when they did decompose at elevated temperatures, no neopentylidene complex could be observed. Addition of neopentyllithium to Mo(NR)Np3CI species (R = Ar, CPh3, or Ad) yielded Mo(NR)(CH-t-Bu)Np2 species, the adamantylimido version of which is unstable toward bimolecular decomposition. Addition of I equivalent of 2,6-diisopropylphenol, 2,6-dimethylphenol, or 3,5-(2,4,6-i-Pr3C6H2)2C6H30H (HIPTOH) to Mo(NCPh3)(CH-t-Bu)Np2 led to formation of Mo(NCPh3)(CH-t-Bu)Np(OR) species, while treatment of Mo(NCPh3)(CH-t- Bu)Np2 with C6FsOH gave Mo(NCPh3)Np3(OC6Fs). The three monophenoxide neopentylidene complexes showed metathesis activity for ring-closing a small selection of amines and an ether. X-ray studies were completed for Mo[N-3,5-(CF3)2C6H3]C14(THF), Mo[N-3,5-(CF3)2C6H3]Np3CI, Mo(NCPh3)Np3CI, and Mo(NCPh3)(CH-t-Bu)Np(OHIPT).(cont.) Addition of I equivalent of 2,6-diisopropylphenol, 2,6-dimethylphenol, or 3,5-(2,4,6-i-Pr3C6H2)2C6H30H (HIPTOH) to Mo(NCPh3)(CH-t-Bu)Np2 led to formation of Mo(NCPh3)(CH-t-Bu)Np(OR) species, while treatment of Mo(NCPh3)(CH-t- Bu)Np2 with C6FsOH gave Mo(NCPh3)Np3(OC6Fs). The three monophenoxide neopentylidene complexes showed metathesis activity for ring-closing a small selection of amines and an ether. X-ray studies were completed for Mo[N-3,5-(CF3)2C6H3]C14(THF), Mo[N-3,5-(CF3)2C6H3]Np3CI, Mo(NCPh3)Np3CI, and Mo(NCPh3)(CH-t-Bu)Np(OHIPT).(cont.) Chapter 3. Reactions of Mo Bispyrrolide Complexes with Enantiomerically Pure Diols: In Situ Catalyst Generation and Studies of Olefin Metathesis Reactions In the Fume Hood. Reactions of bispyrrolide molybdenum complexes Mo(NAd)(CHCMe2Ph)(pyr)2 and Mo(N-2-6-i-Pr2C6H3)(CHCMe2Ph)(pyr)2 with (R)-BiphenH2, and (R)-Benz2BitetH2 were examined (pyr = C4H4N, Benz2BitetH2 = 3,3'-dibenzhydryl-5,5',6,6',7,7',8,8'-octahydro-1,1'- binaphthyl-2,2'-diol). The resulting in situ generated catalysts were studied in three olefin metathesis reactions. These systems were found to be as active and enantioselective as the analogous isolated complexes. When the stock solutions of Mo(NAd)(CHCMe2Ph)(pyr)2, Mo(N- 2,6-i-Pr2C6H3)(CHCMe2Ph)(pyr)2, (R)-BiphenH2, and (R)-Benz2BitetH2 were stored in the fume hood over a period of one month, the in situ prepared catalysts were determined to be nearly identical in terms of their catalytic properties to the catalysts generated in situ in the glovebox.by Tatiana Pilyugina.Ph.D
Topological Data Analysis for Portfolio Management of Cryptocurrencies
Portfolio management is essential for any investment decision. Yet,
traditional methods in the literature are ill-suited for the characteristics
and dynamics of cryptocurrencies. This work presents a method to build an
investment portfolio consisting of more than 1500 cryptocurrencies covering 6
years of market data. It is centred around Topological Data Analysis (TDA), a
recent approach to analyze data sets from the perspective of their topological
structure. This publication proposes a system combining persistence landscapes
to identify suitable investment opportunities in cryptocurrencies. Using a
novel and comprehensive data set of cryptocurrency prices, this research shows
that the proposed system enables analysts to outperform a classic method from
the literature without requiring any feature engineering or domain knowledge in
TDA. This work thus introduces TDA-based portfolio management of
cryptocurrencies as a viable tool for the practitioner
Specifics of Functioning the Phraseological Combination <i>khochesh ne khochesh ‘like it or not’</i>
Specifics of the syntactic functions of phraseological combinations exemplified by the combination khochesh ne khochesh ‘like it or not’ is discussed. Novelty of research consists in that the studied combination is for the first time described in detail from the standpoint of the functional-semantic approach. The topicality of research is determined by happening in the Russian language active process of significant vocabulary being drawn in the composition of service vocabulary and, consequently, is determined by the need of expanded study of the syntactic functions of phraseological combinations as a means of formalizing syntactic relations. Description of studied combination in the dictionaries is presented. A review of scientific studies on syntactic phraseologization is made. The work focuses on the description of semantic structures in which there is the combination khochesh ne khochesh ‘like it or not’. The results of the analysis of the specific environment of combination within its scope in the text are shown. Also particular syntactic relationships, which are expressed by this combination, are commented. Special attention is paid to the analysis of explication of semantic structure of the text. It is emphasized that the analyzed combination is involved in the expression of subjective modality meanings. The author determines that the combination khochesh ne khochesh ‘like it or not’ indicates the presence of two situations, one of which is represented as necessary, having no alternative
Combination ‘v lyubom sluchaye’ (any way): Functioning in Text and Pragmatic Potential
The article is devoted to the description of text structures based on a combination ‘v lyubom sluchaye’ (any way). The analysis was carried out on the material of the texts of the newspaper subcorpus of the National Corpus of the Russian Language. The relevance of the study is due to a multidimensional approach to describing the textual nature of connectivity, including the use of a cognitive-semantic approach to the study of a text from the standpoint of the speaker’s intention, which is consistent with the anthropocentric paradigm of modern linguistics. Within this paradigm, special attention should be paid to transitional linguistic units that occupy an intermediate position between official and significant lexemes and are used by the speaker to form a certain semantic task into a text structure, defined in the article through the concept of a text structure. As an example of such a unit, the combination ‘v lyubom sluchaye’ (any way) is used. It is shown that at a certain position in the text on the border of the utterance, the combination performs the function of a text clip, forms standard text blocks. Particular attention is paid to the analysis of scenarios and models for the presentation of information on the material of newspaper discourse texts. The results of the modality analysis of the of right side the of the structure, which determines the explication of one of the two meanings of the clip ‘free choice’ and ‘universality’ is presented in the article. It is described how the pragmatic potential of the combination is realized in the structure of the textual construction ‘v lyubom sluchaye’ (any way), depending on the nature of the alternative circumstances of the left side of the structure (options, conditions, opinions, assumptions)
To the Question of the Concept of Politics of Memory Actualization in the Modern Russia
The article makes an attempt of the concept of politics of memory actualization in the modern Russia, gives some short theoretical notes about the concept, gives the examples of actualization, politization and institutionalization of the politics of memory at the federal level.В тезисах производится попытка актуализации концепта политики памяти в современной России, дается краткая теоретическая характеристика понятию, приводятся примеры актуализации, политизации и институционализации концепта политики памяти на федеральном уровне
Text Bond TAK ILI INACHE: Types of Constructions and Functional-Semantic Potential
The question of the specificity of text functions of combination tak ili inache ‘anyway’ is covered. The novelty of the study is seen in the fact that for the first time this combination is described in terms of its functioning in the text, the types of contexts characteristic of it are analyzed. The analysis revealed that the combination tak ili inache functions as means of text bond with an alternative-concessive meaning. The relevance of the study is determined by a multidimensional approach to the description of tak ili inache textual nature: this phenomenon is analyzed in terms of semantic, syntactic and communicative-pragmatic features. The characteristic of a combination tak ili inache in explanatory dictionaries and dictionaries of functional parts of speech is presented; the concept of a text bond in a circle of adjacent terms is described. It is established that the text bond tak ili inache is a formal means of organizing text constructions, structure of these constructions is described, especially the implementation of the left and right component. Special attention is paid to the explication of the communicative and pragmatic potential of the bond. On the basis of the analysis of the propositions content of the left part of structures with tak ili inache , the contextual modifications of the studied structures are distinguished. The ability of the bond to create typical text constructions characteristic of journalistic and scientific texts is noted
Topology-based Clusterwise Regression for User Segmentation and Demand Forecasting
Topological Data Analysis (TDA) is a recent approach to analyze data sets
from the perspective of their topological structure. Its use for time series
data has been limited. In this work, a system developed for a leading provider
of cloud computing combining both user segmentation and demand forecasting is
presented. It consists of a TDA-based clustering method for time series
inspired by a popular managerial framework for customer segmentation and
extended to the case of clusterwise regression using matrix factorization
methods to forecast demand. Increasing customer loyalty and producing accurate
forecasts remain active topics of discussion both for researchers and managers.
Using a public and a novel proprietary data set of commercial data, this
research shows that the proposed system enables analysts to both cluster their
user base and plan demand at a granular level with significantly higher
accuracy than a state of the art baseline. This work thus seeks to introduce
TDA-based clustering of time series and clusterwise regression with matrix
factorization methods as viable tools for the practitioner
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