Labyrinth chaos: Revisiting the elegant, chaotic, and hyperchaotic walks

Labyrinth chaos was discovered by Otto Rössler and René Thomas in their endeavour to identify the necessary mathematical conditions for the appearance of chaotic and hyperchaotic motion in continuous flows. Here, we celebrate their discovery by considering a single labyrinth walks system and an array of coupled labyrinth chaos systems that exhibit complex, chaotic behaviour, reminiscent of chimera-like states, a peculiar synchronisation phenomenon. We discuss the properties of the single labyrinth walks system and review the ability of coupled labyrinth chaos systems to exhibit chimera-like states due to the unique properties of their space-filling, chaotic trajectories, what amounts to elegant, hyperchaotic walks. Finally, we discuss further implications in relation to the labyrinth walks system by showing that even though it is volume-preserving, it is not force-conservative

Hyperchaos & labyrinth chaos: revisiting Thomas-Rössler systems

We consider a multidimensional extension of Thomas-R ̈ossler systems, that was inspired by Ren ́e Thomas’ earlier work on biological feedback circuits, and we report on our first results that shows its ability to sustain spatio- temporal behaviour reminiscent of chimera states. The novelty here is that its underlying mechanism is based on “chaotic walks” discovered by Ren ́e Thomas during the course of his investigations on what he called Labyrinth Chaos. We briefly review the main properties of these systems and their chaotic and hyperchaotic dynamics and discuss the simplest way of coupling, necessary for this spatio-temporal behaviour that allows the emergence of complex dynamical behaviours. We also recall Ren ́e Thomas’ memorable influence and interaction with the authors as we dedicate this work to his memory

Subjective Sleep Quality and Daytime Sleepiness Among Greek Nursing Staff: A Multicenter Cross-Sectional Study

Background: Lack of sleep and sleep of poor quality contribute to fatigue, decreased productivity, increased risk of accidents and errors at work. Aim: The aim of the current study is to further investigate the relationship between sleep quality and daytime sleepiness to demographic and work environment characteristics among the nursing stuff. Method and Material:A cross-sectional study was performed on nursing staff, in Athens, from July 2018 to June 2020 focused on characteristics related to poor sleep and sleep disturbance. Results: This cohort investigated 70% poor sleep and 25% excessive daytime sleepiness among nursing staff. Sleep disturbance was related to young age and serving as a ward nurse. Personal as well as departmental and institutional factors affected sleep quality but not excessive daytime sleepiness. Conclusion: Health system managers and nurse leaders should take under consideration not only personal, but also departmental and institutional characteristics when taking support measures to maintain nurses' mental health and patient’s safety

Weak Chaos and the "Melting Transition" in a Confined Microplasma System

We present results demonstrating the occurrence of changes in the collective dynamics of a Hamiltonian system which describes a confined microplasma characterized by long--range Coulomb interactions. In its lower energy regime, we first detect macroscopically, the transition from a "crystalline--like" to a "liquid--like" behavior, which we call the "melting transition". We then proceed to study this transition using a microscopic chaos indicator called the \emph{Smaller Alignment Index} (SALI), which utilizes two deviation vectors in the tangent dynamics of the flow and is nearly constant for ordered (quasi--periodic) orbits, while it decays exponentially to zero for chaotic orbits as $\exp(-(\lambda_{1}-\lambda_{2})t)$, where $\lambda_{1}>\lambda_{2}>0$ are the two largest Lyapunov exponents. During the "melting phase", SALI exhibits a peculiar, stair--like decay to zero, reminiscent of "sticky" orbits of Hamiltonian systems near the boundaries of resonance islands. This alerts us to the importance of the $\Delta\lambda=\lambda_{1}-\lambda_{2}$ variations in that regime and helps us identify the energy range over which "melting" occurs as a multi--stage diffusion process through weakly chaotic layers in the phase space of the microplasma. Additional evidence supporting further the above findings is given by examining the $GALI_{k}$ indices, which generalize SALI (=$GALI_{2}$) to the case of $k>2$ deviation vectors and depend on the complete spectrum of Lyapunov exponents of the tangent flow about the reference orbit.Comment: 21 pages, 7 figures, submitted at PR

Aspirin for in vitro fertilisation

Background: Aspirin is used with the aim of optimising the chance of live birth in women undergoing assisted reproductive technology (ART), despite inconsistent evidence of its efficacy and safety (in terms of intraoperative bleeding during oocyte retrieval and risk of miscarriage). The most appropriate time to commence aspirin therapy and the length of treatment required are also still to be determined. This is the second update of the review first published in 2007. Objectives: To evaluate the effectiveness and safety of aspirin in women undergoing ART. Search methods: We searched the Cochrane Gynaecology and Fertility Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 4) in the Cochrane Library (searched 9 May 2016); the databases MEDLINE (1946 to 9 May 2016) and Embase (1974 to 9 May 2016); and trial registers (ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform search portal). We also examined the reference lists of all known primary studies and review articles, citation lists of relevant publications and abstracts of major scientific meetings, combined with the Cochrane Gynaecology and Fertility Group's search strategy. Selection criteria: Randomised controlled trials on aspirin for women undergoing ART. Data collection and analysis: Two review authors independently assessed trial eligibility and risk of bias and extracted the data. The primary review outcome was live birth. Secondary outcomes included clinical pregnancy, ongoing pregnancy, multiple pregnancy, miscarriage, and other complications associated with IVF/ICSI or with pregnancy and birth. We combined data to calculate risk ratios (RRs) (for dichotomous data) and mean differences (MDs) (for continuous data) and 95% confidence intervals (CIs). Statistical heterogeneity was assessed using the I2 statistic. We assessed the overall quality of the evidence for the main comparisons using GRADE methods. Main results: The search identified 13 trials as eligible for inclusion in the review, including a total of 2653 participants with a mean age of 35 years. Ten studies used a dose of 100 mg and three used 80 mg of aspirin per day. In most of them, aspirin was commenced immediately at the start of down-regulation, while the duration of treatment varied widely. Eight studies provided a placebo for the control group. There was no evidence of a difference between the aspirin group and the group receiving no treatment or placebo in rates of live birth (RR 0.91, 95% CI 0.72 to 1.15, 3 RCTs, n = 1053, I2 = 15%, moderate-quality evidence). In addition, clinical pregnancy rates were also similar for the two groups (RR 1.03, 95% CI 0.91 to 1.17, 10 RCTs, n = 2142, I2 = 27%, moderate-quality evidence); sensitivity analysis, excluding studies at high risk of bias, did not change the effect estimate. There was no evidence of a difference between groups in terms of multiple pregnancy as confirmed by ultrasound (RR 0.67, 95% CI 0.37 to 1.25, 2 RCTs, n = 656, I2 = 0%, low-quality evidence), miscarriage (RR 1.10, 95% CI 0.68 to 1.77, 5 RCTs, n = 1497, I2 = 0%, low-quality evidence), ectopic pregnancy (RR 1.86, 95% CI 0.75 to 4.63, 3 RCTs, n = 1135, I2 = 0%, very low quality evidence) or vaginal bleeding (RR 1.01, 95% CI 0.14 to 7.13, 1 RCT, n = 487, very low quality evidence). Data were lacking on other adverse effects. The overall quality of the evidence ranged from very low to moderate; limitations were poor reporting of study methods and suspected publication bias. Authors' conclusions: Currently there is no evidence in favour of routine use of aspirin in order to improve pregnancy rates for a general IVF population. This is based on available data from randomised controlled trials, where there is currently no evidence of an effect of aspirin on women undergoing ART, as there is no single outcome measure demonstrating a benefit with its use. Furthermore, current evidence does not exclude the possibility of adverse effects. © 2016 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd

Transvaginal ovarian trauma, poor responders and improvement of success rates in IVF: Anecdotal data and a hypothesis

In this report, we propose an intervention capable of improving IVF outcomes in subfertile women with poor ovarian response. This intervention derives from anecdotal data and observations in our daily practice, but most importantly from trials on experimental models and subfertile women with Polycystic Ovarian Syndrome (PCOS). Our hypothesis suggests that transvaginal induction of trauma to the ovary in the cycle preceding IVF should benefit poor ovarian responders and their lowered pregnancy rates by increasing - at least - the number of retrieved oocytes during oocyte retrieval. Up-to-the minute data show that, via this means, there is a unique response of the ovarian surface epithelium and stroma to the induced trauma. The potential pathways of this beneficial response involve an improvement of the raised gonadotrophins to act either through the mechanical reduction of the size of the ovary or through alterations of the hormonal profile by lowering LH, inhibin and local androgen concentrations through hypothalamic-pituitary axis feedbacks, the induction of increased blood flow to the ovaries, a differentiated local immune reaction and a non-elucidated as yet role of reactive oxygen species. In this report, we also describe the technique and the associated possible negative points while we try to point out the needed research steps to ensure its efficiency before it enters daily clinical practice. © 2014 Elsevier Ltd

Mild versus conventional ovarian stimulation for poor responders undergoing IVF/ICSI

Background/Aim: Mild stimulation protocols have been implemented to be offered to subfertile patients who respond poorly to ovarian stimulation. We aimed to compare the efficacy of mild versus conventional gonadotropin-releasing hormone (GnRH)-Agonist and antagonist protocols in poor responders undergoing in vitro fertilization/intra-cytoplasmic sperm injection (IVF/ICSI) cycles. Patients and Methods: A total of 58 poorlyresponding patients were divided into two groups: mild group (n=33), receiving clomiphene citrate 100 mg and 0.25 mg of cetrorelix with 150 IU of gonadotrophins daily; conventional group (n=25), undergoing the long GnRHagonist or-Antagonist protocols. The primary outcome was the number of cumulus oocyte complexes (COCs) retrieved. Results: A lower number of COCs [median (range)=1 (0-4) vs. 3 (0-8.4), p<0.001] was retrieved in the mild stimulation compared to the conventional group. Secondary outcomes favored the conventional group, whereas live birth (9.1% vs. 12%), clinical pregnancy (12.1% vs. 20%) and miscarriage rate (40% vs. 40%) were similar in the two groups. Conclusion: Mild ovarian stimulation is inferior to conventional regimes when applied to poor responders undergoing IVF/ICSI, in terms of the numbers of retrieved COCs

Mild versus conventional ovarian stimulation for poor responders undergoing IVF/ICSI

Background/Aim: Mild stimulation protocols have been implemented to be offered to subfertile patients who respond poorly to ovarian stimulation. We aimed to compare the efficacy of mild versus conventional gonadotropin-releasing hormone (GnRH)-Agonist and antagonist protocols in poor responders undergoing in vitro fertilization/intra-cytoplasmic sperm injection (IVF/ICSI) cycles. Patients and Methods: A total of 58 poorlyresponding patients were divided into two groups: mild group (n=33), receiving clomiphene citrate 100 mg and 0.25 mg of cetrorelix with 150 IU of gonadotrophins daily; conventional group (n=25), undergoing the long GnRHagonist or-Antagonist protocols. The primary outcome was the number of cumulus oocyte complexes (COCs) retrieved. Results: A lower number of COCs [median (range)=1 (0-4) vs. 3 (0-8.4), p<0.001] was retrieved in the mild stimulation compared to the conventional group. Secondary outcomes favored the conventional group, whereas live birth (9.1% vs. 12%), clinical pregnancy (12.1% vs. 20%) and miscarriage rate (40% vs. 40%) were similar in the two groups. Conclusion: Mild ovarian stimulation is inferior to conventional regimes when applied to poor responders undergoing IVF/ICSI, in terms of the numbers of retrieved COCs