Experiments on a periodically forced Belousov-Zhabotinsky chemical reaction show front breakup into a state of spatiotemporal disorder involving continual events of spiral-vortex nucleation and ...destruction. Using the amplitude equation for forced oscillatory systems and the normal form equations for a curved front line, we identify the mechanism of front breakup and explain the experimental observations.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Uniform oscillations in spatially extended systems resonate with temporal periodic forcing within the Arnold tongues of single forced oscillators. The Arnold tongues are wedge-like domains in the ...parameter space spanned by the forcing amplitude and frequency, within which the oscillator's frequency is locked to a fraction of the forcing frequency. Spatial patterning can modify these domains. We describe here two pattern formation mechanisms affecting frequency locking at half the forcing frequency. The mechanisms are associated with phase-front instabilities and a Turing-like instability of the rest state. Our studies combine experiments on the ruthenium catalyzed light-sensitive Belousov-Zhabotinsky reaction forced by periodic illumination, and numerical and analytical studies of two model systems, the FitzHugh-Nagumo model and the complex Ginzburg-Landau equation, with additional terms describing periodic forcing.
Resonance regions similar to the Arnol'd tongues found in single oscillator frequency locking are observed in experiments using a spatially extended periodically forced Belousov-Zhabotinsky system. ...We identify six distinct 2:1 subharmonic resonant patterns and describe them in terms of the position-dependent phase and magnitude of the oscillations. Some experimentally observed features are also found in numerical studies of a forced Brusselator reaction-diffusion model.
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The transition from localized to systemic spreading of bacteria, viruses, and other agents is a fundamental problem that spans medicine, ecology, biology, and agriculture science. We have conducted ...experiments and simulations in a simple one-dimensional system to determine the spreading of bacterial populations that occurs for an inhomogeneous environment under the influence of external convection. Our system consists of a long channel with growth inhibited by uniform ultraviolet (UV) illumination except in a small “oasis”, which is shielded from the UV light. To mimic blood flow or other flow past a localized infection, the oasis is moved with a constant velocity through the UV-illuminated “desert”. The experiments are modeled with a convective reaction-diffusion equation. In both the experiment and model, localized or extinct populations are found to develop, depending on conditions, from an initially localized population. The model also yields states where the population grows everywhere. Further, the model reveals that the transitions between localized, extended, and extinct states are continuous and nonhysteretic. However, it does not capture the oscillations of the localized population that are observed in the experiment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Transgender and gender diverse (TGD) individuals have greater access to genital surgery (GS) with improved insurance coverage and access to trained surgeons and interdisciplinary gender affirming ...providers.
To determine perioperative medical and behavioral health outcomes in transfeminine (TF) individuals undergoing GS with use of a specific gender-affirming hormone therapy (GAHT) algorithm based on individualized risk factor assessment.
Retrospective observational cohort study from 2017-2022. Pre- and post-operative data collected included clinical and biochemical assessment, GAHT regimens, validated behavioral health measures, and post-operative complications.
Single-center tertiary referral center.
183 TF individuals, grouped into estradiol continued (Group 1) vs estradiol temporarily discontinued for 2-6 weeks preoperatively (Group 2).
Venous thromboembolism (VTE) incidence, non-VTE postoperative complication incidence, and change in behavioral health assessments.
The majority of individuals continued estradiol perioperatively Group 1; 138 (75.4%). Individuals who temporarily held estradiol preoperatively Group 2; 45 (24.6%) were statistically older (p < 0.01), had higher incidence of cardiometabolic comorbidities (p < 0.01), and higher Caprini scores (p < 0.01). Group 1 was statistically more likely to use oral estradiol (p < 0.01). One episode (0.05%) of VTE occurred (Group 1). There was no significant difference in postoperative complications or behavioral health measures between groups.
An individualized algorithm for preoperative hormone management for TF GS resulted in perioperative continuation of GAHT for the majority of individuals without significantly increasing the risk for post-operative surgical complications while maintaining stable behavioral health measures perioperatively.
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