Search results for "periodic"

Modelling the evolution of periodicity in the periodical cicadas

2018

Background: Periodical cicadas (Magicicada spp.) have a life cycle that ends with the entire underground nymph population exhibiting a synchronized mass emergence to mate above ground. Previous studies have hypothesized that the periodical cicadas evolved from non-periodical cicadas by switching from a life-cycle length determined by body size to one determined by age. Questions: When can a mutation coding for fixed life-cycle length invade a resident population in which life-cycle length is variable? What determines the length of the fixed cycle? Methods: Numerical analysis of a mathematical model and simulations of an individual-based model. Results: If there is a sufficiently strong pred…

6-Methyluracil: a redetermination of polymorph (II)

2019

6-Methyluracil, C5H6N2O2, exists in two crystalline phases: form (I), monoclinic, space group P21/c [Reck et al. (1988). Acta Cryst. A44, 417–421] and form (II), monoclinic, space group C2/c [Leonidov et al. (1993). Russ. J. Phys. Chem. 67, 2220–2223]. The structure of polymorph (II) has been redetermined providing a significant increase in the precision of the derived geometric parameters. In the crystal, molecules form ribbons approximately running parallel to the c-axis direction through N—H...O hydrogen bonds. The radical differences observed between the crystal packing of the two polymorphs may be responsible in form (II) for an increase in the contribution of the polar canonical forms…

Coexistence of hidden attractors and multistability in counterexamples to the Kalman conjecture

2019

The Aizerman and Kalman conjectures played an important role in the theory of global stability for control systems and set two directions for its further development – the search and formulation of sufficient stability conditions, as well as the construction of counterexamples for these conjectures. From the computational perspective the latter problem is nontrivial, since the oscillations in counterexamples are hidden, i.e. their basin of attraction does not intersect with a small neighborhood of an equilibrium. Numerical calculation of initial data of such oscillations for their visualization is a challenging problem. Up to now all known counterexamples to the Kalman conjecture were const…

Toward modernizing the systematic review pipeline in genetics: efficient updating via data mining

2012

Purpose: The aim of this study was to demonstrate that modern data mining tools can be used as one step in reducing the labor necessary to produce and maintain systematic reviews. Methods: We used four continuously updated, manually curated resources that summarize MEDLINE-indexed articles in entire fields using systematic review methods (PDGene, AlzGene, and SzGene for genetic determinants of Parkinson disease, Alzheimer disease, and schizophrenia, respectively; and the Tufts Cost-Effectiveness Analysis (CEA) Registry for cost-effectiveness analyses). In each data set, we trained a classification model on citations screened up until 2009. We then evaluated the ability of the model to class…

Biodegradable Ultrasmall-in-Nano Gold Architectures: Mid-Period In Vivo Distribution and Excretion Assessment

2018

A Time-Non-Homogeneous Double-Ended Queue with Failures and Repairs and Its Continuous Approximation

2018

We consider a time-non-homogeneous double-ended queue subject to catastrophes and repairs. The catastrophes occur according to a non-homogeneous Poisson process and lead the system into a state of failure. Instantaneously, the system is put under repair, such that repair time is governed by a time-varying intensity function. We analyze the transient and the asymptotic behavior of the queueing system. Moreover, we derive a heavy-traffic approximation that allows approximating the state of the systems by a time-non-homogeneous Wiener process subject to jumps to a spurious state (due to catastrophes) and random returns to the zero state (due to repairs). Special attention is devoted to the cas…

Anti-heroism and Intercultural Hints in David Charles Badham's Travel in Sicily

2009

The paper analyses the discursive features of Charles Badham's travelogues in Sicily in the context of the XIX century Travel Writing development. The travelogues are peculiar in their textual hybridity, blending some of the traditional discursive paradigms of the late Grand Tour travelogues and some of the conventional categories of the exploration and scientific accounts on the imperial frontier proper of the second half of the XIX century. In Badham's travelogues the informational components and a clear subjectiveness of his experience co-exist; far from articulating heroic attitudes, Badham's travelgues deploy an intercultural approach rather than, in Pratt's words (1985), a "monarch-of…

Vžyvannja form v Ukrajini i na Ukrajini u periodyčnych vydannjach rusyniv Bačky i Sremu u mižvojennyj period

2020

This paper analyzes the use of the preposition u and na in locative constructions with the term Ukraine in the language of Rusyns from Bačka and Syrmia in the 20-30s of the XX century. The following periodicals were taken into consideration: the newspaper “Ruski Novini” of the Rusyns Society for Education and the newspaper “Zarja” and “Kalendar - Zarja” of the Cultural and Educational Union of the Rusyns of Yugoslavia. The use of both prepositions before the specified term is attested, and that is in line with the Ukrainian linguistic tradition. The use of these prepositions in locative constructions with terms Podkarpatska Rus, Karpatska Ukrajina and Hornitsa is also considered.

Multiple solutions for a Sturm-Liouville problem with periodic boundary conditions

2013

The main purpose of this paper is to establish the existence of multiple solutions for a Sturm-Liouville problem with periodic boundary conditions. The approach is based on variational methods and multiple critical points theorems