82 research outputs found

    Central Limit Theorem for traces of the resolvents of half-heavy tailed Sample Covariance matrices

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    We consider the spectrum of the Sample Covariance matrix AN:=XNXNN,\mathbf{A}_N:= \frac{\mathbf{X}_N \mathbf{X}_N^*}{N}, where XN\mathbf{X}_N is the P×NP\times N matrix with i.i.d. half-heavy tailed entries and PNy>0\frac{P}{N}\to y>0 (the entries of the matrix have variance, but do not have the fourth moment). We derive the Central Limit Theorem for the Stieltjes transform of the matrix AN\mathbf{A}_N and compute the covariance kernel. Apart from that, we derive the Central Limit Theorem for the Stieltjes transform of overlapping Sample Covariance matrices

    Targeted and untargeted analysis of secondary fungal metabolites by liquid chromatography-mass spectrometry

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    Eigenvalue statistics of Elliptic Volatility Model with power-law tailed volatility

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    In this paper we study an ensemble of random matrices called Elliptic Volatility Model, which arises in finance as models of stock returns. This model consists of a product of independent matrices X=ΣZX = \Sigma Z where ZZ is a TT by SS matrix of i.i.d. light-tailed variables with mean 0 and variance 1 and Σ\Sigma is a diagonal matrix. In this paper, we take the randomness of Σ\Sigma to be i.i.d. heavy tailed. We obtain an explicit formula for the empirical spectral distribution of XXX^*X in the particular case when the elements of Σ\Sigma are distributed as Student's t with parameter 3. We furthermore obtain the distribution of the largest eigenvalue in more general case, and we compare our results to financial data.Comment: 30 pages, 6 figure

    Национально-конфессиональное разнообразие населения в советских проектах и документах, регулировавших погребение

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    This article examines how issues of national and confessional diversity of the country were reflected and resolved in Soviet official documents concerning the funerary sphere. Analysis of such sources as decrees, rules, instructions, regulations and their projects concerning cemeteries and funerals demonstrates that their discourse and content reflected approaches in national politics, changes in the economic course, and objective and subjective conditions at different stages of the country’s history. Methodologically, the issues considered are included in the research contexts of the history of national politics, imperial history, economic history, and the history of Soviet social engineering. Until the end of the Great Patriotic War, despite state-proclaimed atheism and anti-religious campaigns, a targeted elimination of denominational cemeteries was not seriously considered in the context of the campaigns. Rather, their disappearance was a result of growth and redevelopment of cities and, consequently, the “relocation” of cemeteries from the centre to the outskirts and the emergence of new cemeteries. The latter were arranged without considering the national-confessional principle and were often called “international”, which emphasised their difference from the former denominational cemeteries. The emergence of a project in 1946 which divided burial space according to the denominational principle, in fact, proposed the establishment of denominational cemeteries and reflected changes in national policy from the 1930s, i.e. the strengthening of power-state and nationalist tendencies. However, this too radical an approach for state atheism was mitigated in Soviet documents of the late 1940s — 1970s concerning the burial sphere: they recommended to consider “national” customs with regard to the funerary issue and burial space with the prevalence of quasi-secular “clean” form of Sovietness. As the analysis of the 2014–2017 bill demonstrates, the confessional criterion is in demand in Post-Soviet time again as very significant for differentiating burial space and the national and confessional diversity of the population.В статье рассматривается, как проблемы национально-конфессионального разнообразия страны отражались и решались в советских официальных документах, касавшихся погребальной сферы. Анализ таких источников, как декреты, правила, инструкции, положения и их проекты, касавшихся кладбищ и похорон, показывает, что их дискурсы и содержание отражали подходы в национальной политике, смену экономического курса, объективные и субъективные условия разных этапов истории страны. Методологически изучаемые проблемы вписаны в исследовательские контексты истории национальной политики, имперской истории, экономической истории, истории советского социального проектирования. До конца Великой Отечественной войны, несмотря на артикулируемый на государственном уровне атеизм и проводившиеся антирелигиозные кампании, вопрос о целенаправленной ликвидации вероисповедальных кладбищ в контексте этих кампаний серьезно не рассматривался. Их исчезновение оказывалось, скорее, следствием роста и перепланирования городов, и, соответственно, «переноса» кладбищ из центра на окраины, возникновения новых кладбищ. Последние устраивались уже без учета национально-конфессионального принципа, нередко именовались «интернациональными», что подчеркивало их отличие от прежних вероисповедальных кладбищ. Появление проекта 1946 г., разделявшего мортальное пространство по конфессиональному принципу, фактически предлагавшего устройство конфессиональных кладбищ, фиксировало происходившие с 1930-х гг. изменения в национальной политике — усиление державно-государственнических и националистических тенденций. Однако этот слишком радикальный для государственного атеизма подход был смягчен в советских документах конца 1940-х — 1970-х гг., касавшихся погребальной сферы: ими рекомендовался учет «национальных» обычаев в погребальном деле и в погребальном пространстве при превалировании квазисекулярной «чистой» формы советскости. Как показывает анализ законопроекта 2014–2017 гг., конфессиональный критерий вновь был востребован в постсоветское время как весьма значимый для дифференцирования погребального пространства и национально-конфессионального разнообразия населения

    Effect of Temperature on Fretting Fatigue Characteristics of Bismaleimide Matrix

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    For industrial composite structures, fretting friction is a critical problem. Thermosetting resins are promising materials for these structures due to good mechanical and thermal properties. Two mechanisms of the propagation of fatigue cracks in bismaleimide resin, i.e., the effect of the temperature and the type of the stress ate studied

    New insights into electrospray ionization of patulin

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    Patulin is a mycotoxin produced by several fungal species, mainly by Penicillium spp. and Aspergillus spp. Since patulin-producing fungi are widely spread, this toxin has been detected in food (fruit- and vegetable-based products, cereal products, cheese), feed and even in mouldy water-damaged dwellings. Co-occurrence of patulin with other mycotoxins has also been reported [1]. Patulin is commonly analyzed by liquid chromatography with UV detection. Liquid chromatography coupled to mass spectrometry (LC-MS/MS) is considered as a more specific tool for mycotoxin detection and confirmation. However, the implementation of this technique for the determination of patulin, especially in the context of multi-mycotoxin analysis, is limited due to ionization problems. In this study, the effect of different solvents, mobile phase additives and pH on the ionization and fragmentation pattern of patulin was investigated. The preliminary results showed that under alkaline conditions and using methanol as organic modifier, an intense and stable signal for the methanol-adduct of patulin was obtained in the positive electrospray ionization mode. The fragmentation of this protonated methanol-adduct gave a strong and stable product ion signal. The production spectra were overall more useful than those obtained with the protonated or the deprotonated molecule. These findings indicate the possibility of using the protonated methanol-adduct of patulin for its identification and quantification by LC-MS/MS. Further results that will be presented include the optimization, by means of experimental design, of the parameters that have an influence on the formation of the protonated methanol-adduct of patulin and on its fragmentation behaviour, as well as the inclusion of this toxin in a multi-mycotoxin LC-MS/MS method. This study is the first report of the LC-MS/MS determination of patulin using its protonated methanol-adduct. References: [1] Nielsen KF (2003) Mycotoxin production by indoor molds. Fungal Genetics and Biology. 39: 103-117

    Hemilability of phosphine-thioether ligands coordinated to trinuclear Mo3S4 cluster and its effect on hydrogenation catalysis

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    Ligand-exchange reactions of [Mo3S4(tu)8(H2O)]Cl44H2O (tu = thiourea) with (PhCH2CH2)2PCH2CH2SR ligands, where R = Ph (PS1), pentyl (PS2) or Pr (PS3) afford new complexes isolated as [Mo3S4Cl3(PS1)3]PF6 ([1]PF6), [Mo3S4Cl3(PS2)3]PF6 ([2]PF6) and [Mo3S4Cl3(PS3)3]PF6 ([3]PF6) salts in 30-50% yields as the major reaction products. The crystal structures of [1]PF6 and [2]PF6 were determined by X-ray diffraction (XRD) analysis. Each of the three phosphine-thioether ligands is coordinated in a bidentate chelating mode to a different molybdenum atom of the Mo3S4 trinuclear cluster, herewith all the phosphorus atoms of the phosphino-thioether ligand are located trans to the capping sulfur (3-S). A second product that forms in the reaction of [Mo3S4(tu)8(H2O)]Cl44H2O with PS1 corresponds to the neutral [Mo3S4Cl4(PS1)2(PS1*)] complex. Its XRD analysis reveals both bidentate (PS1) and monodentate (PS1*) coordinating modes of the same ligand. In the latter mode the phosphinethioether is coordinated to a Mo atom only via the P atom. All compounds were characterized by 1H, 31P{1H} NMR, electrospray-ionization (ESI) mass spectrometry and cyclic voltammetry (CV). Reactions of [1]PF6, [2]PF6 and [3]PF6 with an excess of Bu4NCl in CD2Cl2 were followed by 31P{1H} NMR. The spectra indicate equilibrium between cationic [Mo3S4Cl3(PSn)3] + and neutral [Mo3S4Cl4(PSn)2(PSn*)] (n = 1, 2) species. The equilibrium constants were determined as 2.5 ± 0.2103 , 43 ± 2 М -1 and 30 ± 2 М -1 (at 25°C) for [1]PF6, [2]PF6 and [3]PF6, indicating quantitative differences in hemilabile behavior of the phosphino-thioether ligands, depending on the substituent at sulfur. Clusters [1]PF6, [2]PF6 and [3]PF6 were tested as catalysts in reduction of nitrobenzene to aniline with Ph2SiH2 under mild conditions. Significant differencies in the catalytic activity were observed, which can be attributed to different hemilabile behavior of the PS1 and PS2/PS3 ligands

    The Sustainable Development of Competitive Enterprises through the Implementation of Innovative Development Strategy

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    The purpose of this article is to develop methodological approaches to the production effectiveness's evaluating and products competitiveness's level estimation to identify risk groups according to the products and producers, to propose targeted measures manufacturers' support, to activate innovative development and minimize potential social impacts. The leading method to study this problem is the method of constructing the matrix of the producers' efficiency and the commodities' competitiveness which allows implement a differentiated approach to the strategies' development of production's innovative development and social risks' minimization. The article proposes a methodological approach to the products competitiveness's level assessment based on the efficiency of production and external conditional factors and identifies the respective groups of competitive and non-competitive commodities and producers, as well as it defines the resource and innovation potential, with further strategy development. The study materials can be used in the management of manufacturing development, both at the level of the industrial enterprises' services and government agencies, to assess the level of products' competitiveness, to create strategies of innovation development, to develop targeted actions for the exports' development. Keywords: commodities' competitiveness, production efficiency, export potential, innovation development JEL Classifications: O31, O34, Q0
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