Predictions of ultra-harmonic oscillations in coupled arrays of limit cycle oscillators

Coupled distinct arrays of nonlinear oscillators have been shown to have a regime of high frequency, or ultra-harmonic, oscillations that are at multiples of the natural frequency of individual oscillators. The coupled array architectures generate an in-phase high-frequency state by coupling with an array in an anti-phase state. The underlying mechanism for the creation and stability of the ultra-harmonic oscillations is analyzed. A class of inter-array coupling is shown to create a stable, in-phase oscillation having frequency that increases linearly with the number of oscillators, but with an amplitude that stays fairly constant. The analysis of the theory is illustrated by numerical simulation of coupled arrays of Stuart-Landau limit cycle oscillators.Comment: 24 pages, 9 figures, accepted to Phys. Rev. E, in pres

Необходимость изучения экологической медицины в высших медицинских учебных заведениях

Optimization problems with cardinality constraints are very difficult mathematical programs which are typically solved by global techniques from discreteoptimization. Here we introduce a mixed-integer formulation whose standard relaxation still has the same solutions (in the sense of global minima) as the underlying cardinality-constrained problem; the relation between thelocal minima is also discussed in detail. Since our reformulation is a mini-mization problem in continuous variables, it allows to apply ideas from thatfield to cardinality-constrained problems. Here, in particular, we therefore also derive suitable stationarity conditions and suggest an appropriate regularization method for the solution of optimization problems with cardinalityconstraints. This regularization method is shown to be globally convergentto a Mordukhovich-stationary point. Extensive numerical results are given to illustrate the behavior of this method

Complete chaotic synchronization in mutually coupled time-delay systems

Complete chaotic synchronization of end lasers has been observed in a line of mutually coupled, time-delayed system of three lasers, with no direct communication between the end lasers. The present paper uses ideas from generalized synchronization to explain the complete synchronization in the presence of long coupling delays, applied to a model of mutually coupled semiconductor lasers in a line. These ideas significantly simplify the analysis by casting the stability in terms of the local dynamics of each laser. The variational equations near the synchronization manifold are analyzed, and used to derive the synchronization condition that is a function of the parameters. The results explain and predict the dependence of synchronization on various parameters, such as time-delays, strength of coupling and dissipation. The ideas can be applied to understand complete synchronization in other chaotic systems with coupling delays and no direct communication between synchronized sub-systems.Comment: 22 pages, 6 figure

Women\u27s perspectives on the ethical implications of non-invasive prenatal testing: A qualitative analysis to inform health policy decisions

Background: Non-Invasive Prenatal Testing (NIPT) is a technology which provides information about fetal genetic characteristics (including sex) very early in pregnancy by examining fetal DNA obtained from a sample of maternal blood. NIPT is a morally complex technology that has advanced quickly to market with a strong push from industry developers, leaving many areas of uncertainty still to be resolved, and creating a strong need for health policy that reflects women\u27s social and ethical values. We approach the need for ethical policy-making by studying the use of NIPT and emerging policy in the province of Ontario, Canada. Methods: Using an adapted version of constructivist grounded theory, we conducted interviews with 38 women who have had personal experiences with NIPT. We used an iterative process of data collection and analysis and a staged coding strategy to conduct a descriptive analysis of ethics issues identified implicitly and explicitly by women who have been affected by this technology. Results: The findings of this paper focus on current ethical issues for women seeking NIPT, including place in the prenatal pathway, health care provider counselling about the test, industry influence on the diffusion of NIPT, consequences of availability of test results. Other issues gain relevance in the context of future policy decisions regarding NIPT, including funding of NIPT and principles that may govern the expansion of the scope of NIPT. These findings are not an exhaustive list of all the potential ethical issues related to NIPT, but rather a representation of the issues which concern women who have personal experience with this test. Conclusions: Women who have had personal experience with NIPT have concerns and priorities which sometimes contrast dramatically with the theoretical ethics literature. These findings suggest the importance of engaging patients in ethical deliberation about morally complex technologies, and point to the need for more deliberative patient engagement work in this area

Time management in a co-housed social rodent species (Arvicanthis niloticus)

Sociality has beneficial effects on fitness, and timing the activities of animals may be critical. Social cues could influence daily rhythmic activities via direct effects on the circadian clock or on processes that bypass it (masking), but these possibilities remain incompletely addressed. We investigated the effects of social cues on the circadian body temperature (Tb) rhythms in pairs of co-housed and isolated grass rats, Arvicanthis niloticus (a social species), in constant darkness (DD). Cohabitation did not induce synchronization of circadian Tb rhythms. However, socio-sexual history did affect circadian properties: accelerating the clock in sexually experienced males and females in DD and advancing rhythm phase in the females in a light-dark cycle. To address whether synchronization occurs at an ultradian scale, we analyzed Tb and activity rhythms in pairs of co-housed sisters or couples in DD. Regardless of pair type, co-housing doubled the percentage of time individuals were simultaneously active without increasing individual activity levels, suggesting that activity bouts were synchronized by redistribution over 24 h. Together, our laboratory findings show that social cues affect individual time allocation budgets via mechanisms at multiple levels of biological organization. We speculate that in natural settings these effects could be adaptive, especially for group-living animals