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Insurance market is an important part of the financial market, the functioning of which helps to protect individuals and legal entities from the negative and stressful effects of today’s unstable economic environment. The purpose of this study is to determine trends in the insurance market in Ukraine and its potential crises.The study found that Ukraine’s insurance market constantly grows, but is volatile and in a state of concentration. The dynamics of most indicators are cyclical, with a cycle length from 4,66 quarters to 14 quarters. The randomized R/S-analysis confirmed the stability of the dynamics of Ukraine’s insurance market and its fractal similarity. Fractal similarity was proved for six out of ten analyzed indicators of the insurance market. In addition, it was confirmed that at the moment of transition from one fractal to another, a trend break occurs. Thus, the emergence of crises on the insurance market of Ukraine is associated with the self-similarity of the dynamics and the coincidence of the moments of bifurcation of certain indicators in its development. A partial crisis on the Ukrainian insurance market at the beginning of 2019 coincided with the bifurcation of the number of concluded insurance contracts, determined based on the results of fractal analysis.Calculations made it possible to conclude that potentially crisis periods for the insurance market of Ukraine fall on Q1-2 2017, Q1 2019, Q1 2020, of which only one was realized (Q1 2019). The nearest potential moments of crises on the insurance market of Ukraine may be the following periods: Q1 2023 and Q1 2026.

Altres ajuts: acords transformatius de la UAB We solve the center-focus problem in a class of piecewise quadratic polynomial differential systems with an invariant straight line. The separation curve is also a straight line which is not invariant. We provide families having at the origin a weak-foci of maximal order. In the continuous class, the cyclicity problem is also solved, being 3 such maximal number. Moreover, for the discontinuous class but without sliding segment, we prove the existence of 7 limit cycles of small amplitude.

In this paper we study planar polynomial Kolmogorov's differential systems X μ { x ˙ = f ( x , y ; μ ) , y ˙ = g ( x , y ; μ ) , with the parameter μ varying in an open subset Λ ⊂ R N . Compactifying X μ to the Poincaré disc, the boundary of the first quadrant is an invariant triangle Γ , that we assume to be a hyperbolic polycycle with exactly three saddle points at its vertices for all μ ∈ Λ . We are interested in the cyclicity of Γ inside the family { X μ } μ ∈ Λ , i.e., the number of limit cycles that bifurcate from Γ as we perturb $\mu.$ In our main result we define three functions that play the same role for the cyclicity of the polycycle as the first three Lyapunov quantities for the cyclicity of a focus. As an application we study two cubic Kolmogorov families, with N = 3 and N = 5 , and in both cases we are able to determine the cyclicity of the polycycle for all μ ∈ Λ , including those parameters for which the return map along Γ is the identity.

The article is devoted to the identification of conceptually identical perceptions of musical time in the cultures of India and Indonesia. The paper considers tala, the Indian category of time, in the context of structuring the parameters of musical compositions in Indian art. Gamelans (Indonesian ensembles of musical instruments) are described in detail as well as the basic principles of organizing musical material in the compositions they perform. The aim of the work is to compare the patterns of perception of the category of time in the cultures of India and Indonesia. The research methodology is based on the principles of an integrated approach that considers the musical traditions of these countries from theoretical and historical-cultural positions. In the process of working on this article, the key role was played by the experience of studying Indian and Indonesian cultures obtained by the authors during scientific internships in India and Indonesia (T.V. Kartashova – institute Shriram Bharatiya Kala Kendra in 2004–2006 and in 2009 (New-Delhi, India); V.U. Antipova studied at the Indonesian Institute of Arts in Yogyakarta under the Darmasiswa Indonesian Scholarship program in the 2017–2018 academic year). The result of the study is the identification of the cyclical nature of musical time in the art of India and Indonesia. It is concluded that in the coordinate systems of different civilizations there are certain intersection points, and often they appear at a conceptual level. The identification of common interpretations of various categories makes it possible to comprehend deep intercivilizational ties, which makes it possible to identify the relatedness of the basics of world understanding in the cultures of South and Southeast Asia.

Oxytocin has been used to treat neurodevelopmental conditions in adolescent patients but possible effects on reproductive development have not been well investigated. The effects of daily intra-nasal oxytocin treatment (12-18months of age) on puberty and fertility were studied in colony-housed, male and female titi monkeys (Plecturocebus cupreus). Body weight, urinary conjugated pregnanes and estrogens (defining cyclicity) in females, and androgens and sperm in urine of in males, were measured from 1 to 3years of age to detect puberty. Serum testosterone was also measured in males at 13, 23 and 33months of age and hemi-castration at 3years of age enabled assessment of testicular morphometry and oxytocin receptor expression. An oxytocin treatment*time interaction suggested a minor, transient suppression in weight gain after treatment ended. Note that females weighed 10% less across all ages. Oxytocin-treated females exhibited early, spurious ovulations but neither regular cyclicity (≈30months) nor pregnancies were affected by treatment. Oxytocin did not affect the pubertal increase in urinary androgen or the first appearance of sperm, which occurred as early as 15months of age. Treatment did delay the puberty-associated rise in serum testosterone in males. All males were pubertal by 22months and all females by 32months of age. Although no major male or female fertility outcome was observed, oxytocin demonstrated some physiological effects through a delay of testosterone secretion in males, induction of precocious ovulation in females, and a suppression of general weight gain for the months following treatment.

We consider polynomial families of ordinary differential equations on $\R^3$, parametrized by the admissible coefficients, for which the origin is an isolated singularity at which the linear part of the system has one non-zero real and two purely imaginary eigenvalues. We derive theorems that bound the maximum number of limit cycles within the center manifold that can bifurcate, under arbitrarily small perturbation of the coefficients, from any center at the origin. The bounds are global in that they apply to the system corresponding to any point on any irreducible component of the center variety in the space of parameters. We also derive theorems for such bounds when attention is confined to a single irreducible component of the center variety. The first and second authors are partially supported by a MEC grant number MTM2016- 80276-P and by a CIRIT grant number 2014 SGR 1204.

The paper examines from an empirical point of view the state of economic sustainability of Romania on the period 2007 - 2017. To this end, a set of macroeconomic indicators for sustainability was used. To be mentioned this set of indicators is elaborated within The Centre for Financial and Monetary Research "Victor Slăvescu", in its annual publication named "Financial stance of Romania". Although the obtained results in the past are coherent with the main macroeconomic dynamics on the analysed period, it seems that these results must be correlated with the so-called cyclical position of the economy, but this analysis will be done in the future. The study puts into evidence the importance of sustainability analyses in addition to the usual descriptive analyses, because they indicate not only the macroeconomic evolution, but also the national economy tendencies from the sustainability perspective.

Hilbert's 16th Problem suggests a concern to the cyclicity of planar polynomial differential systems, but it is known that a key step to the answer is finding the cyclicity of center-focus equilibria of polynomial differential systems (even of order 2 or 3). Correspondingly, the same question for polynomial discontinuous differential systems is also interesting. Recently, it was proved that the cyclicity of (1, 2)-switching FF type equilibria is at least 5. In this paper we prove that the cyclicity of (1, 3)-switching FF type equilibria with homogeneous cubic nonlinearities is at least 3.

В статье автор поднимает вопрос, связанный с оценкой возможности деспотических политических режимов к эффективному существованию в постиндустриальную эпоху. Будучи формой правления, жестко ориентированной на удовлетворение потребностей обеспечения самовластия, деспотия не связана с целью развития или трансформации существующих отношений. Вместе с тем, описываемая ситуация требует выяснения ряда проблем, которые касаются понимания того, чем является деспотия в XXI веке и достигла ли она своего предела. Автор проводит различие между возможными описаниями такой деспотии в качестве гибрида, химеры или симулякра. Отмечается, что третья волна демократизации не привела к исчезновению деспотий, которые продолжили свое существование и готовы к реваншу, чтобы доказать свою состоятельность. Вопрос здесь упирается в то, насколько мир стал другим и могут ли заявить поновому о себе нелинейные эффекты., In the article, the author raises a question related to the assessment of the possibility of despotic political regimes to effectively exist in the post-industrial era. As a form of government that is rigidly focused on meeting the needs of ensuring autocracy, despotism is not associated with the goal of developing or transforming existing relations. At the same time, the described situation requires clarification of a number of problems that relate to understanding what despotism is in the XXI century and whether it has reached its limit. The author distinguishes between possible descriptions of such despotism as a hybrid, chimera, or simulacrum. It is noted that the third wave of democratization did not lead to the disappearance of despotisms, which continued to exist and are ready for revenge to prove their worth. The question here rests on how much the world has become different and whether nonlinear effects can make a new statement about themselves.

Agraïments: This work was done when H. Liang was visiting the Department of Mathematics of Universitat Autònoma de Barcelona. He is very grateful for the support and hospitality. The first author is supported by the NSF of China (No. 11201086 and No. 11401255) and the Excellent Young Teachers Training Program for colleges and universities of Guangdong Province, China (No. Yq2013107). Agraïments: The second author is partially supported by UNAB13-4E-1604. A particular version of the 16th Hilbert's problem is to estimate the number, M(n), of limit cycles bifurcating from a singularity of center-focus type. This paper is devoted to finding lower bounds for M(n) for some concrete n by studying the cyclicity of different weak-foci. Since a weak-focus with high order is the most current way to produce high cyclicity, we search for systems with the highest possible weak-focus order. For even n, the studied polynomial system of degree n was the one obtained by QiuYan2009 where the highest weak-focus order is n^2 n-2 for n=4,6, 18. Moreover, we provide a system which has a weak-focus with order (n-1)^2 for n 12. We show that Christopher's approach Chr2006, aiming to study the cyclicity of centers, can be applied also to the weak-focus case. We also show by concrete examples that, in some families, this approach is so powerful and the cyclicity can be obtained in a simple computational way. Finally, using this approach, we obtain that M(6) 39, M(7) 34 and M(8) 63.

Made available in DSpace on 2020-12-10T19:45:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-15 Ministerio de Economia, Industria y Competitividad - Agencia Estatal de Investigacion (FEDER) Agencia de Gestio d'Ajuts Universitaris i de Recerca Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Brazilian agency FAPEG European Union's Horizon 2020 research and innovation programme Our interest is centered in the study of the number of limit cycles for nonsmooth piecewise linear vector fields on the plane when the switching curve is xy=0. We consider the symmetric case. That is, one vector field defined in the odd quadrants and the other in the even ones. We deal with equilibrium points of center-focus type, with matrices in real Jordan form, in each vector field when the infinity is monodromic. In this case, we provide the center classification at infinity, we prove that the maximum order of a weak focus is five. Moreover, we show the existence of systems exhibiting five limit cycles bifurcating from infinity. (C) 2019 Elsevier Inc. All rights reserved. Univ Estadual Paulista, Dept Matemat, BR-15054000 Sao Jose Do Rio Preto, Brazil Univ Fed Goias, Inst Matemat & Estat, BR-74001970 Goiania, Go, Brazil Univ Autonoma Barcelona, Dept Matemat, E-08193 Barcelona, Spain Univ Estadual Paulista, Dept Matemat, BR-15054000 Sao Jose Do Rio Preto, Brazil Ministerio de Economia, Industria y Competitividad - Agencia Estatal de Investigacion (FEDER): MTM2016-77278-P Agencia de Gestio d'Ajuts Universitaris i de Recerca: 2017 SGR 1617 FAPESP: 2013/24541-0 FAPESP: 2017/03352-6 CAPES: PROCAD 88881.068462/2014-01 CNPq: 308006/2015-1 Brazilian agency FAPEG: 29199/2018 CNPq: PRONEX 2017-10267000508 European Union's Horizon 2020 research and innovation programme: Dynamics-H2020-MSCA-RISE-2017-777911

In this paper, we study the creation of zeros in a certain type of families of functions. The families studied are given by the difference of two basic functions with a translation made in the argument of one of these functions. The problem is motivated by applications in the 16th Hilbert problem and its ramifications. Here, we apply the results obtained to the study of bifurcations of critical periods in the Loud family of quadratic centers. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

In this paper we construct F2-linear codes over Fb2 with length n and dimension n−r where n=rb. These codes have good properties, namely cyclicity, low density parity-check matrices and maximum distance separation in some cases. For the construction, we consider an odd prime p, let n=p−1 and utilize a partition of Zn. Then we apply a Zech logarithm to the elements of these sets and use the results to construct an index array which represents the parity-check matrix of the code. These codes are always cyclic and the density of the parity-check and the generator matrices decreases to 0 as n grows (for a fixed r). When r=2 we prove that these codes are always maximum distance separable. For higher r some of them retain this property. The first author was supported by CAPES (Brazil). The work of the second author was partially supported by Spanish grants AICO/2017/128 of the Generalitat Valenciana and VIGROB-287 of the Universitat d'Alacant. The third and fourth authors were supported by NSERC (Canada). The first, third and fourth authors acknowledge support from FAPESP SPRINT grant 2016/50476-0.

В статье рассматривается цикличность как одно из свойств социально-экономического развития страны. Актуальность этого исследования невозможно переоценить, так как циклические колебания, происходящие под воздействием различных макроэкономических показателей, существенно влияют на экономику страны. Данная работа посвящена анализу развития экономики России на протяжении 2000-2020 годов, опираясь на теорию цикличности экономического развития. Основой анализа являются теории циклов Китчина и Жюгляра, теория Шипоша, также предположение о взаимосвязи различных экономических фаз с показателем уровня ВВП страны.The article considers cyclicality as one of the properties of socio-economic development of the country. The importance of this study cannot be overestimated because cyclical fluctuations that occur under the influence of various macroeconomic indicators significantly affect the country's economy. This work is devoted to the analysis of the development of the Russian economy during 2000-2020, based on the theory of cyclical economic development. The analysis is based on the theory of the Kitchin and Juglar cycles, the Shiposh theory, and the assumption of the interconnectedness of various economic phases with the indicator of the country's GDP level.

By the linearization property of Lipschitz-free spaces, any Lipschitz map $$f : M \rightarrow N$$ between two pointed metric spaces may be extended uniquely to a bounded linear operator $${\widehat{f}} : {\mathcal {F}}(M) \rightarrow {\mathcal {F}}(N)$$ between their corresponding Lipschitz-free spaces. In this note, we explore the connections between the dynamics of Lipschitz self-maps $$f : M \rightarrow M$$ and the linear dynamics of their extensions $${\widehat{f}} : {\mathcal {F}}(M) \rightarrow {\mathcal {F}}(M)$$ . This not only allows us to relate topological dynamical systems to linear dynamical systems but also provide a new class of hypercyclic operators acting on Lipschitz-free spaces.

Central to algorithmic graph theory are the concepts of acyclicity and strongly connected components of a graph, and the related search algorithms. This article is about combining mathematical precision and concision in the presentation of these concepts. Concise formulations are given for, for example, the reflexive-transitive reduction of an acyclic graph, reachability properties of acyclic graphs and their relation to the fundamental concept of “definiteness”, and the decomposition of paths in a graph via the identification of its strongly connected components and a pathwise homomorphic acyclic subgraph. The relevant properties are established by precise algebraic calculation. The combination of concision and precision is achieved by the use of point-free relation algebra capturing the algebraic properties of paths in graphs, as opposed to the use of pointwise reasoning about paths between nodes in graphs.

Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.livsci.2018.01.017; International audience; The present study aimed to investigate the relationships between each step of the reproductive process (cyclicity, estrus, and fertility) and both milk production and body reserves management. The database included 102 studies and 300 treatments collected on electronic databases. Coding for each type of experimental factor enabled within and between experiment variation to be distinguished, and to select subsets of experiments with common objectives in order to avoid inappropriate aggregation of results across studies with very different objectives. Finally, the models were based on limited numbers of experiments (from 14 to 30 treatments originating from 7 to 15 distinct experiments) because (i) only data coded for diet and genetic factors were analyzed, separately (studies on other factors such as milking frequency and parity were too scarce); (ii) a minimum of variation of the explanatory variable was set to enable the quantification of the relationship; (iii) few studies reported comparable reproductive, production and body reserves traits. The results of the meta-analyses showed that the commencement of luteal activity (C-LA) was not associated with milk yield and that the relationship between C-LA and body condition score (BCS) at calving was quadratic (with an optimal BCS at calving around 3.10 on a 0-5 scale). Although the interval from calving to first observed estrus (COE1) is partly composed of CLA, it was not associated with BCS. For each additional 1 kg of milk yield produced at both peak and over the initial 14 weeks of lactation, COE1 was delayed by 1.1 days. The conception rate to first insemination (CRAB.) was reduced by 2.0% (of inseminated cows) and by 2.2% for each additional 1 kg of milk yield at peak and at service respectively. Moreover, CRAM was increased by 38.2% and 22.0% for each additional 1 score of BCS at service and at nadir (i.e. lowest BCS) respectively. Finally, risk of pregnancy (PR) was not associated with milk yield. However, PR was increased by 42.8% (of cows) and 16.8% for each additional unit of BCS at calving and at nadir, respectively. This meta-analysis showed that postpartum cyclicity of dairy cows was mainly associated with BCS at calving, whereas estrus expression was mainly associated with milk yield and fertility with both BCS and milk yield. Genetic and nutritional strategies that target a BCS of 3.10 and limit both BCS loss and peak milk yield could be an effective way to improve reproduction.

This case report aimed to describe cyclic patterns of residual mood symptoms in partially remitted bipolar I patient. In a 24-year-old woman with bipolar I disorder, residual mood symptoms measured by self-rated daily mood chart for 18 months were analyzed using wavelet analysis. A 146-day periodicity was prominent for the first 100 days after discharge. Between 100–200 days, 146-day periodicity was progressively diminished and 21- and 8-day periodicity was prominent. Between 200–516 days, 21-day periodicity was diminished and 85-day periodicity became prominent. This case suggest that bipolar patients might have cyclic residual symptoms with specific frequencies.

In this paper, I analyze the evolution of the Latin adverb/discourse marker NUNC and its Old and Modern French equivalents, or and maintenant, markers whose content-level source meanings are in all cases equivalent to English now. The analysis pays particular attention to the role of metonymic inference, and to bridging contexts. Showing that the three etymologically unrelated markers have remarkably similar (but crucially not identical) uses, both as temporal adjuncts and as pragmatic markers of various types, I argue that the diachronic changes undergone by these three items constitute a semantic/pragmatic cycle of a type that I call “onomasiological” (cf. Hansen 2015, fc). I suggest that cyclic developments at the level of semantics and pragmatics take place because source items that are semantically similar will favor similar types of contextual inferences. Furthermore, the fact that the range of uses of the items under consideration is not necessarily exactly identical from one cycle to the next supports an instructional view of semantics, which affords a central role in the process of meaning construction precisely to inferencing.

One of the outstanding research questions regarding the Mediterranean's Messinian Salinity Crisis (MSC) is whether mechanisms that generated Messinian events also have an expression outside the basin as a result of changes in ocean circulation, tectonics or isostasy. To assess this, a high resolution astronomically calibrated age model for the entire Messinian of the Guadalquivir Basin, on the Atlantic margin of Spain, has been constructed. Cyclic changes in the elemental composition of the Huelva-1 borehole, visualized through XRF, were tuned to astronomical target curves. In some intervals, the tuning was hampered as a consequence of the borehole's proximity to the basin margin, resulting in disturbances of the cyclic record; nevertheless three distinct correlations with Mediterranean events were observed. Firstly, the onset of cyclicity within the borehole, at 7.16 Ma, is synchronous with the first sign of Mediterranean-Atlantic gateway restriction; this may be related to uplift of the Betic corridor. Secondly, the increase in sedimentation rate starting around 5.55 Ma coincides with the end of the acme of the Messinian Salinity Crisis. Lastly, for the first time a lithological expression has been found outside the Mediterranean which may have been generated by the same mechanism that terminated the Messinian Salinity Crisis. This level corresponds with the onset of a pronounced and extensive glauconite layer, indicating a sudden and significant decrease in sedimentation rate. Two causative mechanisms, or a combination of them, are proposed for the interbasinal correlations during the MSC. The first is based on tectonic events in the Betic region that influence sedimentation within the Guadalquivir Basin while altering the Atlantic-Mediterranean connection. The second explains the increase in sedimentation rate at 5.55 Ma as a consequence of local basin infill and the condensation at 5.33 Ma by sediment winnowing as a result of increased current strength with the opening, or deepening, of the Gibraltar Strait. © 2017 Gebrüder Borntraeger, Stuttgart, Germany.

Эта статья посвящена синергетической интерпретации двух циклических те- орий развития общества – Н. Кондратьева и А. Чижевского. Обосновывается идея, что общий ход циклической динамики общества, обнаруженный в этих концепциях, не противоречит синергетическому видению социальной эволюции, поскольку вклю- чает в себя моменты нелинейности и стохастичности., Ця стаття присвячена синергетичній інтерпретації двох циклічних теорій роз- витку суспільства – М. Кондратьєва й О. Чижевського.Обґрунтовується авторська позиція, що активне застосування синергетики до дослідження соціокультурних процесів свідчить про пошук цілісного світоглядного концепту пояснення світу, що вимагає переосмислення накопиченого духовного та інтелектуального досвіду. Виникають передумови нового синтезу фундаментальної науки, філософії і релігії, з’єднання фізики й метафізики, що наближає до форму- вання нового світобачення на сучасних наукових засадах.Показано, що одним із найбільш плідних напрямів у цьому сенсі є синергетична інтерпретація соціальних циклів самоорганізації, які постають як послідовне роз- гортання логіки різних фаз упорядкування соціальних систем, іманентно властивої самій природі цих систем. У такому підході втілюється синергетичне розуміння порядку як процесу, на різних фазах якого діють різні закони структурних змін у системі.Доказується, що методологічним орієнтиром для такого кшталту інтерпре- тації може слугувати опис різних режимів існування складних нелінійних систем у процесі їх самоорганізації – LS-режиму й HS-режиму, наведений О. Князєвою й С. Курдюмовим. У сполученні з тлумаченням структурно-еволюційних змін складно організованих систем у загальнонаукових концепціях (кібернетиці, загальній теорії систем тощо) ці режими можуть бути позначені як режим зародження порядку й режим збереження порядку в єдиному циклі саморозвитку соціальних систем.Обґрунтовується, що послідовно опису етапів зародження порядку й етапів збереження порядку в циклічних теоріях відповідають: у теорії довгих хвиль еконо- мічної кон’юнктури М. Кондратьєва – підвищувальна хвиля (фаза підйому) і пони- жувальна хвиля (фаза спаду); у теорії політичних циклів А. Шлезінгера-молодшого – фаза суспільної цілеспрямованості політичного життя й фаза орієнтації на при- ватні інтереси; у теорії циклів соціокультурної динаміки С. Маслова – аналітичний («лівопівкульний») і синтетичний («правопівкульний») періоди соціального світо- сприйняття; у теорії впливу сонячної активності на соціальну динаміку О. Чижев- ського – періоди посилення й послаблення збудливості сонячної активності тощо.Розгляд у статті основних положень концепції М. Кондратьєва й О. Чижевсько- го дозволив зробити висновок, що загальний перебіг циклічної динаміки суспільства, виявлений у цих концепціях, не суперечить синергетичному баченню соціальної ево- люції, оскільки містить у собі моменти нелінійності й стохастичності., This article deals with the synergetic interpretation of the two cyclical theories of social development – by N. Kondratiev and by A. Chizhevsky. The idea of these conceptions that the general course of the cyclical dynamics of society does not contradict the synergetic vision of social evolution since it includes features of nonlinearity and stochasticity is grounded.

It is well known that the cyclicity of a Hopf bifurcation in continuous quadratic polynomial differential systems in \begin{document}$\mathbb{R}^2$\end{document} is \begin{document}$\end{document} . In contrast here we consider discontinuous differential systems in \begin{document}$\mathbb{R}^2$\end{document} defined in two half-planes separated by a straight line. In one half plane we have a general linear center at the origin of \begin{document}$\mathbb{R}^2$\end{document} , and in the other a general quadratic polynomial differential system having a focus or a center at the origin of \begin{document}$\mathbb{R}^2$\end{document} . Using averaging theory, we prove that the cyclicity of a Hopf bifurcation for such discontinuous differential systems is at least 5. Our computations show that only one of the averaged functions of fifth order can produce 5 limit cycles and there are no more limit cycles up to sixth order averaged function.

The activation of the hypothalamic–pituitary axis is critical for the initiation and maintenance of reproductive cycles in pigs and is influenced by a number of factors, such as nutrition, metabolism and gonadal steroids. Kisspeptin is a neuropeptide that is expressed in discrete regions of the porcine hypothalamus and is positioned to mediate the action of many of these factors. The expression of kisspeptin in the pig hypothalamus does not appear to be regulated by gonadal steroids in the same way as other species. It is unclear if kisspeptin is mediating nutritional or metabolic effects on gonadotropin secretion in pigs as it takes large deficits in feed intake or BW to affect hypothalamic expression of the KISS1 gene in the porcine hypothalamus. There appears to be little genetic diversity in kisspeptin or its receptor that is useful for improving reproduction in swine. Both peripheral and central injection of kisspeptin strongly stimulates the secretion of gonadotropin hormones, LH and FSH, in gilts. Similarly, synthetic analogues have been developed and showed potential promise as tools to manage reproductive cycles in gilts and sows. Review of the literature nonetheless reveals that research on kisspeptin and its function in controlling reproduction in pigs has lagged that of other livestock species.

A polynomial system of differential equations on the plane with a singularity at which the eigenvalues of the linear part are complex can be placed, by means of an affine transformation and a rescaling of time, in the form $\dot x = \lambda x - y + P(x, y)$, $\dot y = x + \lambda y + Q(x, y)$. The problem of determining, when $\lambda = 0$, whether the origin is a spiral focus or a center dates back to Poincaré. This is the center problem. We discuss an approach to this problem that uses methods of computational commutative algebra. We treat generalizations of the center problem to the complex setting and to higher dimensions. The theory developed also has bearing on the cyclicity problem at the origin, the problem of determining bounds on the number of isolated periodic orbits that can bifurcate from the origin under small perturbation of the coefficients of the original system. We also treat this application of the theory. Some attention is also devoted to periodic solutions on center manifolds and their bifurcations.

Технологии циклического управления реализуемыми бизнеc-процессами в рамках кибернетического подхода и концепции VUCA-мира. Указываются возможные направления постиндустриального и информационного развития стран Европы в зависимости от развития социоэкономических отношений. Проводится анализ ряда социокультурных причин, обуславливающих всё увеличивающееся отставание РФ от передовых стран при реализации государственной инновационной политики., The technologies of cyclic control of realizable business-processes within the framework of the cybernetic approach and the concept of VUCA-world are considered. The possible directions of post-industrial and information development of European countries are indicated, depending on the development of socioeconomic relations. A number of sociocultural reasons are analyzed that determine the ever-increasing lagging of the Russian Federation from the advanced countries in the implementation of the state innovation policy.

RESUMO A fitoterapia, abrangendo o uso popular e empírico de plantas medicinais no combate e prevenção de doenças, deve ser aliada a estudos científicos que comprovem a eficácia e segurança desses compostos. No Brasil, a ampla biodiversidade vegetal da região nordeste favorece o uso e estudo de plantas com potenciais terapêuticos. A Aroeira do Sertão (Myracrodruon urundeuva Allem.) é uma espécie pertencente à família Anacardiaceae, comum no semiárido, desde o Piauí até Minas Gerais. Seu uso é diverso e disseminado por todo o País, sendo indispensáveis estudos de suas potencialidades e riscos. Devido à ampla utilização da Myracrodruon Urundeuva de forma empírica, este trabalho tem por objetivo a pesquisa de efeitos tóxicos com doses repetidas do extrato etanólico de Myracrodruon urundeuva Allem. (EEMU) e sua influência no ciclo estral de ratas Wistar. No protocolo de toxicidade subaguda foram utilizadas 25 ratas Wistar, divididas em 5 grupos (n=5), tratadas com diferentes doses do EEMU (125, 250, 500 e 1000 mg/kg) e água destilada (controle) por um período de 28 dias. Nesse período foram realizadas mensurações do consumo de água e ração e avaliação comportamental. Esses animais foram avaliados diariamente quanto a fase do ciclo estral, por meio de esfregaço vaginal a fresco, sendo observada a frequência de cada fase bem como o intervalo interestro. As ratas foram anestesiadas e o sangue foi coletado para a realização dos ensaios bioquímicos. Em seguida, foram eutanasiadas para coleta e avaliação dos órgãos internos. Durante o período de avaliação, não foram observadas alterações de comportamento, nem de consumo de água ou ração. A evolução ponderal dos animais não diferiu entre os grupos tratados. A concentração sérica de ALT foi maior nos animais tratados com EEMU 1000 mg/kg. As ratas tratadas com o extrato não apresentaram alterações significativas na frequência das fases do ciclo estral bem como duração do estro e intervalo entre estros, quando comparadas ao grupo controle. Os resultados obtidos neste estudo não apontam alterações tóxicas significativas, sistêmicas ou sobre o ciclo estral, de ratas Wistar tratadas com o extrato, nas doses avaliadas, por um período de 28 dias. ABSTRACT The herbal medicine, comprising the popular and empirical use of medicinal plants in combating and preventing diseases, should be combined with scientific studies that prove the effectiveness and safety of these compounds. In Brazil, the vast plant biodiversity of the Northeast favors the use and study of plants with therapeutic potential. Aroeira (Myracrodruon urundeuva Allem.) is a species of the Anacardiaceae family, common in the semiarid region, from Piauí to Minas Gerais. Its use is diverse and widespread throughout the country, making studies of its potential and risks necessary. Due to the wide use of Myracrodruon urundeuva in an empirical form, this paper aims to research toxic effects with repeated doses of Myracrodruon urundeuva Allem.ethanol extract (EEMU) and its influence on the estrous cycle of female Wistar rats. In a subacute toxicity protocol 35 female Wistar rats were used, divided into 5 groups (n=5) treated with different doses of EEMU (125, 250, 500 and 1000 mg/kg) and distilled water (control) for 28 days. In this period measurements of water intake, feed consumption were carried out and a behavioral assessment was performed. The estrous cycles of these animals were evaluated daily by fresh vaginal smear, it the frequency of each phase as well as the inter-estrus intervals were observed. The rats were anesthetized and blood was collected for the biochemical assays. Then they were euthanized for the collection and evaluation of internal organs. During the evaluation period, there were no observed behavioral changes nor were the water or food consumption variations. The weight gain of the animals did not differ between treatment groups. The serum ALT was higher in animals treated with EEMU 1000 mg/kg. The rats treated with the extract showed no significant changes in the frequency of the phases of the estrous cycle, estrus duration and estrus interval when compared to the control group. The results of this study do not indicate significant toxic alterations, neither systemic nor on the estrous cycle in female rats treated with the extract, at the evaluated doses, over a period of 28 days.

Variations of the sea ice cover in the Tatar Strait (Japan Sea) in 1951-2014 are analyzed in connection with changes of surface atmospheric pressure, geopotential height H500, and air temperature over eastern Asia and the North-West Pacific. Besides, water circulation and spatial distribution of the sea ice and water temperature in the southern Tatar Strait are described in detail for March of 2014 and 2015 using satellite data (MODIS/Terra, MODIS/Aqua, MTSAT1). Dominant periodicities are revealed for the whole time series of ice cover and its parts (1951-1982 and 1983-2014): the 5-year cycle dominated in January-March for the former period, and the 2-year cycle - for the latter period, whereas long-term cycles (7-10 years) were weaker. Significant trend is found for the 1950-1982 but it is not significant for the 1983-2014. The ice cover variation correlated with changes of the Siberian High strength in the 1951-1982 but mostly with atmosphere processes over south Asia and the Okhotsk Sea in the 1983-2014, that’s why the 2-year cycle was stronger in the latter case. Mechanism of «cold» winters formation is considered in detail for a case of 2001, and the mechanism of «warm» winters formation - for the 1991, 2008, 2014, and 2015. Two scenarios are available for the latter case of low ice cover: i) abnormally southern position of the trough on H500 surface over the Okhotsk Sea; and ii) the ridge on H500 surface over the Japan Sea and adjacent continental areas. The ice cover fluctuations in 2015 are forecasted and this forecast comes true for February and March. Features of spatial distribution of the ice, water dynamics and thermal regime are considered in detail for the southern Tatar Strait in March 2014 and 2015 using satellite data.

We describe a method for bounding the cyclicity of the class of monodromic singularities of polyn omial planar families of vector fields X λ with an analytic Poincar e first return map having a polynomial Bautin ideal B in the ring of polynomials in the parameters λ of the family. This class includes the nondegenerate centers, generic nilpotent centers and also some degenerate centers. This method can work even in the case in which B is not radical by studying the stabilization of the integral closures of an ascending chain of polynomial ideals that stabilizes at B. The approach is based on computational algebra methods for determining a minimal basis of the integral closurē B of B. As far as we know, the obtained cyclicity bound is the minimum found in the literature. The first author was partially supported by a MINECO grant number MTM2014-53703-P and by a CIRIT grant number 2014 SGR 1204.

Современный период социально-экономического развития страны сопровождается активным ростом предпринимательских структур. В связи с этим, особую значимость приобретает устойчивое их развитие в контексте влияния факторов и территориальных условий. Авторами определено, что развитие является процессом многогранным, многоаспектным и опирается на экстенсивное и интенсивное использование факторов. При этом существенным условием в обеспечении развития предпринимательства является не только способ использования факторов, но и источники финансирования его ресурсов. Исходя из этого, авторами были выделены четыре типа развития предпринимательства. На основании проведенного исследования, предложена типология факторов, оказывающих влияние на устойчивое развитие предпринимательства в контексте цикличности., The modern period of socio-economic development of the country is accompanied by an active growth of business structures. In this regard, their sustainable development in the context of the influence of factors and territorial conditions is of particular importance. The authors determined that development is a multi-faceted, multi-faceted process and is based on extensive and intensive use of factors. At the same time, an essential condition in ensuring the development of entrepreneurship is not only the way of using factors, but also the sources of financing of its resources. On this basis, the authors identified four types of business development. On the basis of the conducted research, a typology of factors influencing the sustainable development of entrepreneurship in the context of cyclicity is proposed.

This work provides upper bounds on the cyclicity of the centers on center manifolds in the well-known Lorenz family, and also in the Chen and Lü families. We prove that at most one limit cycle can be made to bifurcate from any center of any element of these families, perturbing within the respective family, with the exception of one specific Lorenz system where the cyclicity increases. We also show that this bound is sharp. The first and second authors are partially supported by a MINECO grant number MTM2017-84383-P and an AGAUR grantnumber 2017SGR-1276.

The article contains the typology of views expressed by Pitirim Sorokin about cyclical alterations of socio-cultural systems in European civilization developed in his concept of sociocultural dynamics. The concept is used by the author to examine and analyze the evolution of the esthetic categories such as the form of art and the content. It is suggested that deconstruction of the unity of the content and its fragmentation inevitably cause transformations in a form of art that is bound to carry out the functions of the content. Summarizing the ideas of Pititim Sorokin about the cyclicity of three cultural super-systems – ideational, idealistic and sensory – the author of the article stresses the significance of the fourth stage – the one of eclectic art - within the dynamics of cultural alterations. In his studies, Sorokin features the eclectic stage, though he does not include it (nor do his followers) into the global process of fluctuating changes of society. The author of the article aims at highlighting the importance of the transitional stage of eclectic art in the space of altering super-systems and proposes to assign to it the status of the fourth super-system in the cycle of fluctuating changes

This article is devoted to the study of variability of electricity generation from renewable sources. Due to the natural features of the generation,it characterized by cyclical fluctuations, as well as the influence of random factors. Availability of information about the basic factors and methods of modeling allows the selection of generating equipment, which provides consumers with the highest quality and uninterrupted energy.

We study Dirichlet-type spaces $\mathfrak{D}_{\alpha}$ of analytic functions in the unit bidisk and their cyclic elements. These are the functions $f$ for which there exists a sequence $(p_n)_{n=1}^{\infty}$ of polynomials in two variables such that $\|p_nf-1\|_{\alpha}\to 0$ as $n\to \infty$. We obtain a number of conditions that imply cyclicity, and obtain sharp estimates on the best possible rate of decay of the norms $\|p_nf-1\|_{\alpha}$, in terms of the degree of $p_n$, for certain classes of functions using results concerning Hilbert spaces of functions of one complex variable and comparisons between norms in one and two variables. We give examples of polynomials with no zeros on the bidisk that are not cyclic in $\mathfrak{D}_{\alpha}$ for $\alpha>1/2$ (including the Dirichlet space); this is in contrast with the one-variable case where all non-vanishing polynomials are cyclic in Dirichlet-type spaces that are not algebras ($\alpha\le 1$). Further, we point out the necessity of a capacity zero condition on zero sets (in an appropriate sense) for cyclicity in the setting of the bidisk, and conclude by stating some open problems., Comment: 20 pages

This paper concerns the study of small-amplitude limit cycles that appear in the phase portrait near an unfolded fake saddle singularity. This degenerate singularity is also known as an impassable grain. The canonical form of the unperturbed vector field is like a degenerate flow box. Near the singularity, the phase portrait consists of parallel fibers, all but one of which have no singular points, and at the singular fiber, there is one node. We demonstrate different techniques in order to show that the cyclicity is bigger than or equal to two when the canonical form is quadratic. (C) 2014 Elsevier Inc. All rights reserved. The first author acknowledges the support of FWO Vlaanderen (Grant number G093910). The third author was supported by the MINECO/FEDER MTM2008-03437, MTM2013-40998-P and UNAB10-4E-378 grants, by the AGAUR 2014SGR568 grant, and by the European Community FP7-PEOPLE-2012-IRSES-316338 and by the FP7-PEOPLE-2012-IRSES-318999 grants. We thank Jorge Galan for numerical simulations confirming the existence of a homoclinic connection.

Let $A=\mathbb{F}_{q}[T]$ , where $\mathbb{F}_{q}$ is a finite field, let $Q=\mathbb{F}_{q}(T)$ , and let $F$ be a finite extension of $Q$ . Consider $\phi$ a Drinfeld $A$ -module over $F$ of rank $r$ . We write $r=hed$ , where $E$ is the center of $D:=\operatorname{End}_{\overline{F}}(\phi)\otimes Q$ , $e=[E:Q]$ , and $d=[D:E]^{\frac{1}{2}}$ . If $\wp$ is a prime of $F$ , we denote by $\mathbb{F}_{\wp}$ the residue field at $\wp$ . If $\phi$ has good reduction at $\wp$ , let $\bar{\phi}$ denote the reduction of $\phi$ at $\wp$ . In this article, in particular, when $r\neq d$ , we obtain an asymptotic formula for the number of primes $\wp$ of $F$ of degree $x$ for which $\bar{\phi}(\mathbb{F}_{\wp})$ has at most $(r-1)$ cyclic components. This result answers an old question of Serre on the cyclicity of general Drinfeld $A$ -modules. We also prove an analogue of the Titchmarsh divisor problem for Drinfeld modules.

Knowledge of the cyclicity features in the fluctuations of river runoff, duration and nature of the low-water and high-water period interchange in one or other river basins, and especially their prediction provides invaluable assistance in the planning and sound management of the water resources, improving the operational efficiency of the hydropower, reclamation and other water facilities . Currently, the interest in the study of long-term cyclical fluctuations in the river runoff, as well as patterns of fluctuations of its underlying factor highly increased due to their use in the long-term forecasts. Time series of annual water runoff for basins of Tisza, Dniester and Prut rivers were estimated with the use of mathematical tools, methodological framework of which is based on a statistical means of summarizing, systemization of the input data, evaluation methods of time random sets of the runoff characteristics, methods of analysis of the time series variability and manifestation of their structure.DOI: http://dx.doi.org/10.5755/j01.erem.73.1.15799

Agraïments: The author is partially supported by NSFC grant #11471228 (X. Chen), NSFC grant # 11501083 (Z. Wang), and NSFC grants # 11231001 and # 11221101 (W. Zhang). Since the independence of focal values is a sufficient condition to give a number of limit cycles arising from a center-focus equilibrium, in this paper we consider a restricted independence to a parametric curve, which gives a method not only to increase the lower bound for the cyclicity of the center-focus equilibrium but also to be available when those focal values are not independent. We apply the method to a nondegenerate cubic center-focus variety and prove that the cyclicity reaches its an upper bound.

We study the cyclicity of vectors $u$ in $\ell^p(\mathbb{Z})$. It is known that a vector $u$ is cyclic in $\ell^2(\mathbb{Z})$ if and only if the zero set, $\mathcal{Z}(\widehat{u})$, of its Fourier transform, $\widehat{u}$, has Lebesgue measure zero and $\log |\widehat{u}| \not \in L^1(\mathbb{T})$, where $\mathbb{T}$ is the unit circle. Here we show that, unlike $\ell^2(\mathbb{Z})$, there is no characterization of the cyclicity of $u$ in $\ell^p(\mathbb{Z})$, $1, Comment: Australian Journal of Mathematical Analysis and Applications, Austral Internet Publishing, A Para{\^i}tre

The relevance of this topic is associated with the diversity of causes behind crisis processes in economics and the individuality of each particular crisis. This necessitates classifying them in a detailed fashion. The present downturn is a manifestation of the cyclicity of the development of the global economic system amid present-day globalization and the established architecture of the institutional space. The formal (legislation, contractual rules, corporate norms, etc.) and non-formal institutes (rules, customs, traditions, behavior as a whole, etc.), undergoing changes in their structure and mechanisms, caused the emergence of financial innovations whose yield surpassed that of the real sector of the economy multifold. This facilitated the concentration of money in financial markets and transforming them into a thing-in-itself. The theory of economic cycles is one of the theories of economic dynamics which explain the movement of the national economy. While the theory of economic growth explores factors and conditions for growth as a long-term trend, the theory of cycles deals with causes behind fluctuations in economic activity through time. Results. In accordance with the aims of this study, the authors established that crises can have the following causes: objective, which are associated with the cyclical development of the system, modernization and restructuring needs, and the impact of external factors, and subjective, which reflect errors in management, shortcomings in the organization of production, and the imperfections of innovation and investment policy. A crisis can take its course manifestly and be easily detected or can be inconspicuous and take its course in a latent form. The most dangerous are crises that affect the system as a whole. In a situation of this kind, there forms a train of complex issues resolving which depends on the timeliness of detecting them and professionalism in managing the organization, municipal education, and the state.

A stochastic characterization of a hydrocarbon reservoir, constituted by a sedimentary sequence of sandstones interbbeded with siltstones and shales, has been performed. The stratigraphic unit studied here mainly comprises the C4 sands of the Misoa Formation, located in the Lama Field, Maracaibo Lake (Venezuela). A Markov Chain algorithm, based on the definition of genetic lithofacies relationships along stratigraphic columns, was developed. The application of the Monte Carlo stochastic method using this algorithm, to log data from 11 wells, allowed the generation of pseudo sequences at 20 new locations. This algorithm was able to properly model pseudo stratigraphic sequences and to quantify the relative facies percentage, showing a 82% confidence level related to the proportional content of sediments at a test well. The net sand map obtained integrating the stratigraphic columns, derived from the well information, and the Markov pseudo-columns, suggests the presence of sand bodies with a northeast-southwest orientation that agree with previous geological studies in the area. This map could help in the definition of prospective zones in the field. The existence of stratigraphic memory along the evaluated columns was recognized after applying the algorithm. The embedded Markov method used in the cyclicity analysis of the whole area indicates cyclic transitions just from sandstones to siltstones and from shales to siltstones. Hence for the study area, on average, fining upward and coarsening upward processes can be identified with the Markovian approach, as was expected for the tide-dominated deltaic system associated to the analyzed reservoir.