Reconciling and Validating the Ashworth-Davies Doppler Shifts of a Translating Mirror

We simplify the Ashworth-Davies special relativistic theory of a uniformly translating mirror with an arbitrary angle of incidence and direction of propagation in the non-relativistic limit. We show that it is in good agreement with a more intuitive derivation that only considers the constancy of the speed of light. We confirm the theory with phase-insensitive frequency measurements using a liquid crystal light valve

A phenomenological approach to normal form modeling: a case study in laser induced nematodynamics

An experimental setting for the polarimetric study of optically induced dynamical behavior in nematic liquid crystal films has allowed to identify most notably some behavior which was recognized as gluing bifurcations leading to chaos. This analysis of the data used a comparison with a model for the transition to chaos via gluing bifurcations in optically excited nematic liquid crystals previously proposed by G. Demeter and L. Kramer. The model of these last authors, proposed about twenty years before, does not have the central symmetry which one would expect for minimal dimensional models for chaos in nematics in view of the time series. What we show here is that the simplest truncated normal forms for gluing, with the appropriate symmetry and minimal dimension, do exhibit time signals that are embarrassingly similar to the ones found using the above mentioned experimental settings. The gluing bifurcation scenario itself is only visible in limited parameter ranges and substantial aspect of the chaos that can be observed is due to other factors. First, out of the immediate neighborhood of the homoclinic curve, nonlinearity can produce expansion leading to chaos when combined with the recurrence induced by the homoclinic behavior. Also, pairs of symmetric homoclinic orbits create extreme sensitivity to noise, so that when the noiseless approach contains a rich behavior, minute noise can transform the complex damping into sustained chaos. Leonid Shil'nikov taught us that combining global considerations and local spectral analysis near critical points is crucial to understand the phenomenology associated to homoclinic bifurcations. Here this helps us construct a phenomenological approach to modeling experiments in nonlinear dissipative contexts.Comment: 25 pages, 9 figure

Spatiotemporal pulses in a liquid crystal optical oscillator

A nonlinear optical medium results by the collective orientation of liquid crystal molecules tightly coupled to a transparent photoconductive layer. We show that such a medium can give a large gain, thus, if inserted in a ring cavity, it results in an unidirectional optical oscillator. Dynamical regimes with many interacting modes are made possible by the wide transverse size and the high nonlinearity of the liquid crystals. We show the generation of spatiotemporal pulses, coming from the random superposition of many coexisting modes with different frequencies

Frailty and post-operative delirium influence on functional status in patients with hip fracture: the GIOG 2.0 study

Background: This study analyzes the effect of frailty and Post-Operative Delirium (POD) on the functional status at hospital discharge and at 4-month follow-up in patients with hip fracture (HF). Methods: Multicenter prospective observational study of older patients with HF admitted to 12 Italian Orthogeriatric centers (July 2019-August 2022). POD was assessed using the 4AT. A 26-item Frailty Index (FI) was created using data collected on admission. The outcome measures were Cumulated Ambulation Score (CAS) ≤ 2 at discharge and a telephone-administered CAS ≤ 2 after 4 months. Poisson regression models were used to assess the effect of frailty and POD on outcomes. Results: 984 patients (median age 84 years, IQR = 79–89) were recruited: 480 (48.7%) were frail at admission, 311 (31.6%) developed POD, and 158 (15.6%) had both frailty and POD. In a robust Poisson regression, frailty alone (Relative Risk, RR = 1.56, 95% Confidence Intervals, CI 1.19–2.04, p = 0.001) and its combination with POD (RR = 2.57, 95% CI 2.02–3.26, p < 0.001) were associated with poor functional status at discharge. At 4-month follow-up, the combination of frailty with POD (RR 3.65, 95% CI 1.85–7.2, p < 0.001) increased the risk of poor outcome more than frailty alone (RR 2.38, 95% CI 1.21–4.66, p < 0.001). Conclusions: POD development exacerbates the negative effect that frailty exerts on functional outcomes in HF patients

Sexual Functioning and Opioid Maintenance Treatment in Women. Results From a Large Multicentre Study

Opioid maintenance treatment (OMT) is the most widespread therapy for both females and males opioid addicts. While many studies have evaluated the OMT impact on men’s sexuality, the data collected about the change in women’s sexual functioning is still limited despite the fact that it is now well-known that opioids - both endogenous and exogenous - affect the endocrine system and play an important role in sexual functioning. The present study aims to determine how OMT with buprenorphine (BUP) or methadone (MTD) affects sexual health in women; examining also any possible emerging correlation between sexual dysfunction (SD), type of opioid and patients’ mental health. This multi-center study case recruited 258 female volunteers attending Italian public Addiction Outpatients Centers that were stabilized with OMT for at least 3 months. SD was assessed with the Arizona Sexual Experience Scale. The twelve-item General Health Questionnaire was used to assess participants’ mental health conditions. The results show that 56.6% of women receiving OMT for at least 3 months presented SD without significant differences between MTD e BUP groups. The majority of the subjects with SD have a poorer quality of intimate relationships and worse mental health than the average. To the best of our knowledge, the present study is the largest report on the presence of SDs in women as a side effects of MTD and BUP used in OMT. Since SDs cause difficulties in intimate relationships, lower patients’ quality of life and interfere with OMT beneficial outcomes, we recommend that women undertaking an opioid therapy have routine screening for SD and we highlight the importance to better examine opioid-endocrine interactions in future studies in order to provide alternative potential treatments such as the choice of opioid, opioid dose reduction and hormone supplementation

Precision Doppler measurements with steep dispersion

Controlling the group velocity of light is a valuable resource for quantum and classical optical processing and high performance sensor technologies. In this context, slow-light (SL) and the associated steep dispersion have been proposed to increase the sensitivity of certain types of interferometers. Here, we show that the interaction of two intensity-balanced light beams in a SL medium can be used to detect Doppler shifts with extremely high sensitivity. By using this effect in a liquid crystal light-valve, we have been able to measure Doppler shifts as low as 1 μHz with an integration time of only 1 s. The shot noise limited sensitivity inversely depends on the steepness of the beam-coupling dispersive response. This method allows for remote sensing of very slowly moving objects with a linear response over 5 orders of magnitude. © 2013 Optical Society of America OCIS codes: (280.3340) Laser Doppler velocimetry; (260.2030) Dispersion; (190.4223) Nonlinear wave mixing