Nonlinear mechanics with photonic crystal nanomembranes

Optomechanical systems close to their quantum ground state and nonlinear nanoelectromechanical systems are two hot topics of current physics research. As high-reflectivity and low mass are crucial features to improve optomechanical coupling towards the ground state, we have designed, fabricated and characterized photonic crystal nanomembranes, at the crossroad of both topics. Here we demonstrate a number of nonlinear effects with these membranes. We first characterize the nonlinear behavior of a single mechanical mode and we demonstrate its nonlocal character by monitoring the subsequent actuation-related frequency shift of a different mode. We then proceed to study the underlying nonlinear dynamics, both by monitoring the phase-space trajectory of the free resonator and by characterizing the mechanical response in presence of a strong pump excitation. We observe in particular the frequency evolution during a ring-down oscillation decay, and the emergence of a phase conjugate mechanical response to a weaker probe actuation. Our results are crucial to understand the full nonlinear features of the PhC membranes, and possibly to look for nonlinear signatures of the quantum dynamics

2D photonic-crystal optomechanical nanoresonator

We present the optical optimization of an optomechanical device based on a suspended InP membrane patterned with a 2D near-wavelength grating (NWG) based on a 2D photonic-crystal geometry. We first identify by numerical simulation a set of geometrical parameters providing a reflectivity higher than 99.8 % over a 50-nm span. We then study the limitations induced by the finite value of the optical waist and lateral size of the NWG pattern using different numerical approaches. The NWG grating, pierced in a suspended InP 265 nm-thick membrane, is used to form a compact microcavity involving the suspended nano-membrane as end mirror. The resulting cavity has a waist size smaller than 10 $\mu$m and a finesse in the 200 range. It is used to probe the Brownian motion of the mechanical modes of the nanomembrane

High-finesse Fabry-Perot cavities with bidimensional Si3_3N4_4 photonic-crystal slabs

Light scattering by a two-dimensional photonic crystal slab (PCS) can result in dramatic interference effects associated with Fano resonances. Such devices offer appealing alternatives to distributed Bragg reflectors or filters for various applications such as optical wavelength and polarization filters, reflectors, semiconductor lasers, photodetectors, bio-sensors, or non-linear optical components. Suspended PCSs also find natural applications in the field of optomechanics, where the mechanical modes of a suspended slab interact via radiation pressure with the optical field of a high finesse cavity. The reflectivity and transmission properties of a defect-free suspended PCS around normal incidence can be used to couple out-of-plane mechanical modes to an optical field by integrating it in a free space cavity. Here, we demonstrate the successful implementation of a PCS reflector on a high-tensile stress Si$_3$N$_4$ nanomembrane. We illustrate the physical process underlying the high reflectivity by measuring the photonic crystal band diagram. Moreover, we introduce a clear theoretical description of the membrane scattering properties in the presence of optical losses. By embedding the PCS inside a high-finesse cavity, we fully characterize its optical properties. The spectrally, angular, and polarization resolved measurements demonstrate the wide tunability of the membrane's reflectivity, from nearly 0 to 99.9470~$\pm$ 0.0025 \%, and show that material absorption is not the main source of optical loss. Moreover, the cavity storage time demonstrated in this work exceeds the mechanical period of low-order mechanical drum modes. This so-called resolved sideband condition is a prerequisite to achieve quantum control of the mechanical resonator with light

Old Questions and New Evidence from Social Sequence Analysis

In what ways do dual-earner couples organize their workdays and how do they (de)synchronize their daily activities? Using a multichannel sequence analysis approach, the paper tackles these questions. We consider the couples' division of work-family activities in holistic terms by setting it within the context of everyday life, that is, the overall temporal pattern of combination of His and Her multiple activities. Our multichannel sequence analysis approach is based on a Lexicographic Index that seeks to overcome some optimal matching limits of the sequence analysis. The case-study concerns how Italian dual-earner couples organize their daily activities (sleep, personal care, work, moving, housework, free time), during a typical Monday to Friday work day, 7.00 am to 10.00 pm. The analysis, carried out using the data from the 2008 Italian Census on Time Use (the last one available), involves 873 couples where both partners filled the given diaries on the very same day. All the analyses confirm the idea that dual-earner couples package their life time mainly in accordance with their jobs and eventual children management. Moreover, the analyses show that this time packaging changes in relation to the level of education, social class and the occupational sector of the couple

Patient Perceptions of Medical Students’ Involvement in Clinical Classes: A Cross-Sectional Survey

Krzysztof Kaliszewski, Szymon Makles, Agnieszka Fr&aogon;tczak, Micha&lstrok; Kisiel, Patrycja Lipska, Agata Stebel Department of General, Minimally Invasive and Endocrine Surgery, Wroclaw Medical University, Wroclaw, 50-556, PolandCorrespondence: Szymon Makles, Tel +48 662 761 377, Email [email protected]: A crucial aspect of the education of prospective medical professionals is their interaction with patients. The study aimed to explore patients’ perspectives on the interaction between medical students and themselves. It sought to understand how patients perceive this dynamic within clinical classes. The goal was to gather insights into the most favorable behavior and demeanor of medical students during these sessions, with the overarching objective of enhancing patient comfort.Material and Methods: The authors collected a total of 403 surveys from patients of a teaching hospital, regarding their perception of students as healthcare providers. The participants ranged in age from 18 to 92. 53.83% of the participants were female, and 46.17% were male. The surveys were collected between April 8th, 2022, and August 10th, 2022. The results of the anonymous survey undergone statistical analyses using the Mann‒Whitney U-test for comparing two groups and the Kruskal‒Wallis test for comparing more than two groups, because the Shapiro‒Wilk test indicated that the data did not follow a normal distribution.Results: The study delved into patients’ assessments of students’ external presentation, adherence to behavioral norms, empathetic qualities, consideration during intimate examinations, and preferences for the organization of clinical classes. Our research indicates notable differences in responses based on age. Specifically, the senior demographic prioritizes students’ external presentation, communication and the utilization of courteous language more often than younger individuals (p< 0.05). Attendees exhibit varying levels of interest in participating in educational sessions with students based on the ward. Significantly, individuals in the gynecology ward display the least enthusiasm for engagement (p< 0.05). Notably, the majority of patients perceive their involvement in the education of future healthcare professionals to be essential (83.38%).Conclusion: The study found that generally, patients voluntarily engage in educational classes with students. The relationship between patients and students is amicable, and the majority of students display a respectful demeanor toward patients. Nonetheless, preserving patient confidentiality and ensuring the proper management of classes remain persistent issues. This is particularly crucial, especially when the clinical classes pertain to intimate and personal health matters of a patient. Upholding and enriching the organization of such sessions, along with the attentiveness and knowledge of medical students regarding patient comfort, assumes heightened significance.Keywords: medical education, clinical teaching, student-patient relationship, patients’ opinions on students, patient partner