Emotional expression and empathy in an online peer support platform.

Online peer groups are a popular channel for mental health support, but the evidence for their effectiveness is mixed. The present study focused on empathy to better identify which supporters' comments regulated seekers' distress. We also explored how seekers' emotions may shape supporters' empathy. Posts (N = 7,646) published on an online peer support platform ("Emotional first aid [ERAN]") were sourced. Supporters' empathy (empathic concern, personal distress, exploration, and interpretation) and seekers' emotional expressions (soft negative, hard negative, and positive) were coded. We hypothesized that (1) empathic concern, exploration, and interpretation (but not personal distress) would predict better seekers' emotions (lower negative emotions and greater positive ones); (2) support seekers' soft negative and positive emotions would predict supporters' empathic concern and cognitive empathy (i.e., exploration and interpretation); but that (3) hard negative emotions would predict supporters' personal distress. A set of cumulative mixed models revealed that empathic concern predicted more seekers' positive emotions. However, cognitive empathy predicted more negative seekers' emotions. Seekers' soft negative emotions predicted greater expressions of supporters' empathy (of all types). Finally, seekers' positive emotions predicted more supporters' empathic concern and less personal distress, but also predicted less cognitive empathy (i.e., exploration). A secondary analysis found that this pattern of results differed to some extent as a function of the supporters' role as anonymous peers or the professional moderator. These findings suggest that empathy is a key component in online mental support platforms and that it may make online interactions more effective through emotional regulation. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Fluid structure interaction with contact surface methodology for evaluation of endovascular carotid implants for drug-resistant hypertension treatment.

Drug-resistant hypertensive patients may be treated by mechanical stimulation of stretch-sensitive baroreceptors located in the sinus of carotid arteries. To evaluate the efficacy of endovascular devices to stretch the carotid sinus such that the induced strain might trigger baroreceptors to increase action potential firing rate and thereby reduce systemic blood pressure, numerical simulations were conducted of devices deployed in subject-specific carotid models. Two models were chosen--a typical physiologic carotid and a diminutive atypical physiologic model representing a clinically worst case scenario--to evaluate the effects of device deployment in normal and extreme cases, respectively. Based on the anatomical dimensions of the carotids, two different device sizes were chosen out of five total device sizes available. A fluid structure interaction (FSI) simulation methodology with contact surface between the device and the arterial wall was implemented for resolving the stresses and strains induced by device deployment. Results indicate that device deployment in the carotid sinus of the physiologic model induces an increase of 2.5% and 7.5% in circumferential and longitudinal wall stretch, respectively, and a maximum of 54% increase in von Mises arterial stress at the sinus wall baroreceptor region. The second device, deployed in the diminutive carotid model, induces an increase of 6% in both circumferential and longitudinal stretch and a 50% maximum increase in von Mises stress at the sinus wall baroreceptor region. Device deployment has a minimal effect on blood-flow patterns, indicating that it does not adversely affect carotid bifurcation hemodynamics in the physiologic model. In the smaller carotid model, deployment of the device lowers wall shear stress at sinus by 16% while accelerating flow entering the external carotid artery branch. Our FSI simulations of carotid arteries with deployed device show that the device induces localized increase in wall stretch at the sinus, suggesting that this will activate baroreceptors and subsequently may control hypertension in drug-resistant hypertensive patients, with no consequential deleterious effects on the carotid sinus hemodynamics.

Fiber-guided CO2 laser surgery in an animal model.

OBJECTIVE: This study tested a newly developed flexible fiber for CO(2) laser surgery. BACKGROUND DATA: The lack of a flexible delivery system with the current CO(2) laser has limited its surgical application. We conducted in vitro and in vivo studies by using the skin tissue model of animals to test a new laser fiber system. METHODS: In an in vitro study, the acute thermal effect of laser surgery using this new fiber was tested and compared on fresh porcine skin at 3.0-5.0-W laser power and at 0.3-0.5-mm spot size. In the in vivo experiments, the healing process of the skin incisions and wounds was followed microscopically in 16 rats, at post-operative days 2, 6, 12, and 21 after the laser surgery with 3.0-W power and 0.5-mm spot size. RESULTS: The results from the in vitro tissue showed limited thermal damage to neighboring tissue. In the in vivo study, there was rapid postoperative healing. CONCLUSION: Our findings indicate that this fiber system, at least with the laser parameters used in this study, appears to be an effective and feasible alternative for CO(2) laser surgery. It has great potential for development of office-based surgery under local anesthesia.

Surgical utility of a new carbon dioxide laser fiber: functional and histological study.

OBJECTIVES/HYPOTHESIS: The objective was to investigate the functional and histological properties of surgical procedures using a new carbon dioxide (CO2) laser fiber. STUDY DESIGN: In vitro and in vivo animal models. METHODS: In vitro experiments using porcine true vocal cord and arytenoid cartilage were designed to study the histological effects of using a photonic band-gap fiber assembly for CO2 laser energy delivery. Continuous and pulsed-wave settings at different wattages were tested. In vivo endoscopic surgery on canine larynges and buccal mucosa were performed to examine functional and short-term healing when performing photonic band-gap fiber assembly-assisted laser surgery. RESULTS: In vitro experiments showed consistent cutting with the photonic band-gap fiber assembly using either straight or 90 degrees bent-tip fibers. The surrounding tissue in these experiments showed little collateral thermal damage with the average range of thermal width from 14.1 to 18.8 microm in vocal cords and from 5.2 to 10.5 microm in cartilage. Similarly, thermal depth ranged from 28.0 to 350.0 microm in vocal cords and from 269.7 to 739.6 microm in cartilage. In vivo experiments demonstrated ease in maneuvering and flexibility for cutting. There was minimal blood loss, smoke plume, or carbonaceous debris. There were no postprocedural complications. Normal oral intake was noted on postprocedural day 1. There was no evidence of stridor or respiratory distress. Seven days after the procedure, re-epithelialization was complete in the buccal incisions and nearly completed in the laryngeal incisions. CONCLUSION: The photonic band-gap fiber assembly produced reliable results in cutting with functional characteristics representing an improvement over current technology. The device shows promise as an effective tool for minimally invasive procedures that are amenable to use of the CO2 laser.

Analysis of mode structure in hollow dielectric waveguide fibers.

In this paper, we analyze the electromagnetic mode structure of an OmniGuide fiber-a hollow dielectric waveguide in which light is confined by a large index-contrast omnidirectional dielectric mirror. In particular, we find that the modes in an OmniGuide fiber are similar to those in a hollow metallic waveguide in their symmetries, cutoff frequencies, and dispersion relations. We show that the differences can be predicted by a model based on a single parameter-the phase shift upon reflection from the dielectric mirror. The analogy to the metal waveguide extends to the transmission properties, resulting in the identification of the TE01 mode as the lowest-loss mode of the OmniGuide fiber.

Dispersion tailoring and compensation by modal interactions in OmniGuide fibers.

We present a method for dispersion-tailoring of OmniGuide and other photonic band-gap guided fibers based on weak interactions ("anticrossings") between the core-guided mode and a mode localized in an intentionally introduced defect of the crystal. Because the core mode can be guided in air and the defect mode in a much higher-index material, we are able to obtain dispersion parameters in excess of 500,000 ps/nm-km. Furthermore, because the dispersion is controlled entirely by geometric parameters and not by material dispersion, it is easily tunable by structural choices and fiber-drawing speed. So, for example, we demonstrate how the large dispersion can be made to coincide with a dispersion slope that matches commercial silica fibers to better than 1%, promising efficient compensation. Other parameters are shown to yield dispersion-free transmission in a hollow OmniGuide fiber that also maintains low losses and negligible nonlinearities, with a nondegenerate TE01 mode immune to polarization-mode dispersion (PMD). We present theoretical calculations for a chalcogenide-based material system that has recently been experimentally drawn.