articles+ search results

Entoptic phenomena are visual artifacts arising from the interaction of light with the specific anatomic structure of the human eye. While they are usually too subtle to actually enable additional visual abilities, their perception can provide indirect information on the physiological conditions of the visual system. Among the most famous ones, Haidinger's brushes consist in the appearance of a yellowish bow tie perceived in the presence of linearly polarized white light and originate from the particular spatial distribution of dichroic carotenoid molecules forming a sort of embedded radial polarizer in the foveal region. In this work, we develop a compact and versatile optical setup for the psychophysical analysis of the perceptual threshold of such entoptic effect. The tests performed on a group of 113 healthy individuals under conditions of maximum contrast (blue light) reveal the capability to perceive an average polarization degree around 16%. The developed prototype outlines a new optical platform to train the users in the perception of the phenomenon and infer information on the polarization-degree sensitivity of the human visual system.
(Copyright © 2022 Elsevier Ltd. All rights reserved.)

Electrodes, Ion-Selective Electrodes, Ions, Potassium, Potentiometry, Printing, Three-Dimensional, Sodium, Internet of Things, and Robotics

We report automated fabrication of solid-contact sodium-selective (Na + -ISEs) and potassium-selective electrodes (K + -ISEs) using a 3D printed liquid handling robot controlled with Internet of Things (IoT) technology. The printing system is affordable and can be customized for the use with micropipettes for applications such as drop-casting, biological assays, sample preparation, rinsing, cell culture, and online analyte monitoring using multi-well plates. The robot is more compact (25 × 30 × 35 cm) and user-friendly than commercially available systems and does not require mechatronic experience. For fabrication of ion-selective electrodes, a carbon black intermediate layer and ion-selective membrane were successively drop-cast on the surface of stencil-printed carbon electrode using the dispensing robot. The 3D-printed robot increased ISE robustness while decreasing the modification time by eliminating manual steps. The Na + -ISEs and K + -ISEs were characterized for their potentiometric responses using a custom-made, low-cost (<$25) multi-channel smartphone-based potentiometer capable of signal processing and wireless data transmission. The electrodes showed Nernstian responses of 58.2 ± 2.6 mV decade -1 and 56.1 ± 0.7 mV decade -1 for Na + and K + , respectively with an LOD of 1.0 × 10 -5  M. We successfully applied the ISEs for multiplexed detection of Na + and K + in urine and artificial sweat samples at clinically relevant concentration ranges. The 3D-printed pipetting robot cost $100 and will pave the way for more accessible mass production of ISEs for those who cannot afford the expensive commercial robots.
(Copyright © 2022 Elsevier B.V. All rights reserved.)

Equipment Design, Phantoms, Imaging, Software, Algorithms, and Magnetic Resonance Imaging methods

Purpose: An automated algorithm for generating realizable MR gradient and shim coil layouts based on the boundary element method is presented here. The overall goal is to reduce postprocessing effort and thus enable for rapid prototyping of new coil designs. For a given surface mesh and target field, the algorithm generates a connected, non-overlapping wire path.
Methods: The proposed algorithm consists of several steps: Stream function optimization, two-dimensional surface projection, potential discretization, topological contour sorting, opening and interconnecting contours, and finally adding non-overlapping return paths. Several technical parameters such as current strength, inductance and field accuracy are assessed for quality control.
Results: The proposed method is successfully demonstrated in four different examples. All exemplary results demonstrate high accuracy with regard to reaching the respective target field. The optimal discretization for a given stream function is found by generating multiple layouts while varying the input parameter values.
Conclusion: The presented algorithm allows for a rapid generation of interconnected coil layouts with high flexibility and low discretization error. This enables to reduce the overall post-processing effort. The source code of this work is publicly available ( https://github.com/Philipp-MR/CoilGen).
(© 2022 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Animals, Aquaculture, Ergonomics methods, Farmers, Feasibility Studies, Humans, Pilot Projects, Seafood, Bivalvia, Low Back Pain therapy, Occupational Diseases prevention control, and Self-Management

Objectives. Lower back pain (LBP) is extremely prevalent in seafood harvesters who often have limited or no access to ergonomic consultation, occupational health support and rehabilitation services. This pilot study aimed to describe a participatory ergonomic approach and determine the feasibility and extent of adoption of self-management strategies in clam farmers with LBP. Methods. A rapid prototype participatory ergonomic approach was used to develop context-specific self-management strategies. Options to adjust lifting and repetitive stress were introduced using video clips, demonstrations and discussions in the workplace. Workers chose and implemented three strategies for 8 weeks with weekly reminders. Survey and qualitative data from focus groups were analyzed. Results. Team strategies were the most popular, but individual options were used more often. Strategies were considered feasible, acceptable and relatively easy to use. Strategies were implemented relatively consistently, and most improved productivity with decreased pain. Challenges for uptake included changing habit, culture and team dynamics. Conclusions. Participatory rapid prototyping provided a feasible and efficient option to introduce strategies for clam farmers with small teams, variable work processes and workloads, and time restrictions. Strategies were considered acceptable and easy to use, and most increased productivity. These methods show potential for future research.

The growing use of 3D printing in the biomedical sciences demonstrates its utility for a wide range of research and healthcare applications, including its potential implementation in the discipline of breath analysis to overcome current limitations and substantial costs of commercial breath sampling interfaces. This technical note reports on the design and construction of a 3D-printed mouthpiece adapter for sampling exhaled breath using the commercial respiration collector for in-vitro analysis (ReCIVA) device. The paper presents the design and digital workflow transition of the adapter and its fabrication from three commercial resins (Surgical Guide, Tough v5, and BioMed Clear) using a Formlabs Form 3B stereolithography (SLA) printer. The use of the mouthpiece adapter in conjunction with a pulmonary function filter is appraised in comparison to the conventional commercial silicon facemask sampling interface. Besides its lower cost - investment cost of the printing equipment notwithstanding - the 3D-printed adapter has several benefits, including ensuring breath sampling via the mouth, reducing the likelihood of direct contact of the patient with the breath sampling tubes, and being autoclaveable to enable the repeated use of a single adapter, thereby reducing waste and associated environmental burden compared to current one-way disposable facemasks. The novel adapter for breath sampling presented in this technical note represents an additional field of application for 3D printing that further demonstrates its widespread applicability in biomedicine.
(© 2022. The Author(s).)

Background: Facial deformities often demand reconstructive surgery and the placement of three-dimensional (3D) printed craniomaxillofacial prostheses. Prostheses manufacturing requires patients' computed tomography (CT) images. Poor quality images result in incorrectly sized prostheses, necessitating repeat imaging and refitting. The Centre for Rapid Prototyping and Manufacturing (CRPM) produces most facial prostheses in South Africa but does not have a prescribed optimised CT protocol. Therefore, this study was undertaken.
Methods: A collection of CRPM STLs used in the design and manufacturing of craniomaxillofacial prostheses is available. The image quality of stereolithography (STL) files of CRPM CT scans was evaluated to determine what constitutes good image quality. This collection was scrutinised for inclusion in the image quality evaluation. After scrutiny, 35 STLs of individuals ≥15 years of age were selected and included metadata attached to the DICOM file. Furthermore, only STLs created without manipulation by the same designer were included in the collection. Before the qualitative evaluation of the STLs, eight different critical anatomical reference points (CARPs) were identified with the assistance of an expert team. A visual acuity rating scale of three categories was devised for each CARP, where 1 was allocated to poor visual acuity, 2 to partial, and 3 to good visual acuity. Similarly, rating scales were devised for the presence of concentric rings and the overall impression score awarded by the two designers involved in the design and manufacturing of the prostheses. This stereolithography measurement rubric (SMR) was then applied to the 35 STLs by a team of three experts, including the two designers, during a structured evaluation session. The scores were used to calculate summary and inferential statistics.
Results: Scores grouped around the central rating of partial visual acuity. The three evaluators' mean total CARP scores ranged from 13.1 to 14.4 (maximum possible score 24), while the mean total CARP + ring scores ranged from 15.8 to 17.1 (maximum possible score 27). No significant differences were detected between the evaluators' scores.
Conclusion: This SMR appears to be the first of its kind. This image quality assessment of STLs provides the groundwork for finer CT image quality evaluation to formulate a CT imaging protocol for the CRPM to design and manufacture accurate internal cranial prostheses.
(© 2022. The Author(s).)

Purpose: Navigational strategies create a scenario whereby percutaneous needle-based interventions of the liver can be guided using both pre-interventional 3D imaging datasets and dynamic interventional ultrasound (US). To score how such technologies impact the needle placement process, we performed kinematic analysis on different user groups.
Methods: Using a custom biopsy phantom, three consecutive exercises were performed by both novices and experts (n = 26). The exercise came in three options: (1) US-guidance, (2) US-guidance with pre-interventional image-registration (US + Reg) and (3) US-guidance with pre-interventional image-registration and needle-navigation (US + Reg + Nav). The traveled paths of the needle were digitized in 3D. Using custom software algorithms, kinematic metrics were extracted and related to dexterity, decision making indices to obtain overall performance scores (PS).
Results: Kinematic analysis helped quantifying the visual assessment of the needle trajectories. Compared to US-guidance, novices yielded most improvements using Reg (PS avg(US)  = 0.43 vs. PS avg(US+Reg)  = 0.57 vs. PS avg(US+Reg+Nav)  = 0.51). Interestingly, the expert group yielded a reversed trend (PS avg(US)  = 0.71 vs PS avg(US+Reg)  = 0.58 vs PS avg(US+Reg+Nav)  = 0.59).
Conclusion: Digitizing the movement trajectory allowed us to objectively assess the impact of needle-navigation strategies on percutaneous procedures. In particular, our findings suggest that these advanced technologies have a positive impact on the kinematics derived performance of novices.
(© 2022. The Author(s).)

Magnetic Phenomena, Microscopy, Electron, Scanning, Imaging, Three-Dimensional methods, and Spectrometry, Mass, Secondary Ion

The structural, morphological, and chemical characterization of samples is of utmost importance for a large number of scientific fields. Furthermore, this characterization very often needs to be performed in three dimensions and at length scales down to the nanometer. Therefore, there is a stringent necessity to develop appropriate instrumentational solutions to fulfill these needs. Here we report on the deployment of magnetic sector secondary ion mass spectrometry (SIMS) on a type of instrument widely used for such nanoscale investigations, namely, focused ion beam (FIB)-scanning electron microscopy (SEM) instruments. First, we present the layout of the FIB-SEM-SIMS instrument and address its performance by using specific test samples. The achieved performance can be summarized as follows: an overall secondary ion beam transmission above 40%, a mass resolving power ( M /Δ M ) of more than 400, a detectable mass range from 1 to 400 amu, a lateral resolution in two-dimensional (2D) chemical imaging mode of 15 nm, and a depth resolution of ∼4 nm at 3.0 keV of beam landing energy. Second, we show results (depth profiling, 2D imaging, three-dimensional imaging) obtained in a wide range of areas, such as battery research, photovoltaics, multilayered samples, and life science applications. We hereby highlight the system's versatile capability of conducting high-performance correlative studies in the fields of materials science and life sciences.

Face surgery, Fibula, Humans, Maxilla surgery, Surgical Flaps blood supply, and Reconstructive Surgical Procedures methods

Purpose: Midface reconstruction poses a complex set of challenges for reconstructive surgeons. The optimal midface reconstruction must possess a durable underlying bone construct capable of integrating dental implants. Facial contour is restored by the overlying microvascular soft tissue reconstruction with reestablishment of the oral cavity. A plethora of microvascular flaps used in clinical practice have been described including those harvested from the iliac crest, scapula, fibula, forearm and back (latissimus dorsi). The objective was to share our experiences with each of these treatment options that have continued to evolve over time for the benefit of patients.
Methods: Our institution has over three decades of experience in reconstructing complex midface defects and this article summarizes midface reconstruction from an evolutionary perspective (for type II, III and IV defect; Browns classification, Supplementary Table I). We broadly divide this into (i) flaps supplied by the subscapular system (ii) autologous reconstruction with titanium mesh and (iii) fibula microvascular flaps using 3D planning.
Results: The advantages and disadvantages for each approach are discussed (Supplementary Table II).
Conclusion: In the future, it is expected that 3D planning coupled with rapid prototyping, intraoperative navigation and CT imaging will become standard procedural practice.
(© 2022. Crown.)

Curriculum, Humans, Schools, Medical, Surveys and Questionnaires, Education, Medical, Undergraduate, and Students, Medical psychology

Problem: The extent of medical student unwellness is well documented. Learner distress may impact patient care, workforce adequacy, and learners' performance and personal health. The authors describe the philosophy, structure, and content of the novel REACH (Recognize, Empathize, Allow, Care, Hold each other up) curriculum and provide a preliminary evaluation.
Approach: The REACH curriculum is a mandatory, longitudinal well-being curriculum for first- and second-year medical students at the Medical College of Wisconsin (MCW) designed to prepare them for the emotional life of being a physician. The curriculum uses a framework, core concepts, and skills from the field of trauma stewardship. It builds on effective medical student well-being interventions (e.g., mindfulness-based training) and the sharing of personal stories by instructors during didactic and small-group sessions that are integrated into the regular MCW curriculum. During the first 2 years of implementation (2018-2019 and 2019-2020), the curriculum was evaluated using mid- and postcurriculum student surveys.
Outcomes: Over 700 students have completed the REACH curriculum as of March 2022. Overall, most students who responded to the surveys in 2018-2020 reported that they felt the REACH curriculum material was important, that the curriculum met their expectations for a quality medical school course, and that they would recommend other schools incorporate a similar curriculum. Respondents to the 2019-2020 postcurriculum survey indicated the REACH curriculum helped them develop self-care (84% [85/101]), mindfulness (76% [76/101]), and help-seeking (71% [72/101]) skills.
Next Steps: The initial outcomes show that integrating a mandatory well-being curriculum is feasible and acceptable to medical students. The authors plan to examine the relationships between student-reported well-being metrics, academic and clinical performance data, and professional identity formation. They are also prototyping electronic dashboards that will allow students to interact with their well-being data to promote timely help-seeking and behavior change.
(Copyright © 2022 by the Association of American Medical Colleges.)