There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

비만아 부모의 돌봄 경험: q 방법론

A novel self-regulating parylene micro valve is presented in this paper with potential applications for biomedical flow controls. Featuring a free-floating bendable valve disk and two-level valve seat, this surface-micromachined polymeric valve accomplishes miniature pressure/flow rate regulation in a band-pass profile stand-alone without the need of power sources or active actuation. Experimental data of underwater testing results have successfully demonstrated that the microfabricated in-channel valve can regulate water flow at 0-80 mmHg and 0-10 muL/min pressure/flow rate level, which is perfectly suitable for biomedical and lab-on-a-chip applications. For example, such biocompatible microvalve can be incorporated in ocular implants for control of eye fluid drainage to fulfill intraocular pressure (IOP) regulation in glaucoma patients.

/pdf/floating-disk-parylene-microvalve-for-self-regulating-40mjmgad17.pdf

Floating-disk parylene microvalve for self-regulating biomedical flow controls

Choosing the optimal instruments and parameters for vitrectomy has become increasingly challenging because of the variety of modifications and improvements recently introduced. Small-gauge vitreous instruments have improved pars plana vitrectomy considerably. These new instruments minimize surgically induced trauma to ocular tissue, resulting in quicker recovery and less postoperative discomfort for the patient.1 On the other hand, decreasing instrument size imposes significant constraints on the functionality of the surgical instruments. 2

Efforts to improve the efficiency of smaller diameter vitreous cutters have focused on increasing cut speed, maximizing cutting port surface area, and enlarging the diameter of the internal shaft to enable higher flow rates.3 Ultra high-speed cutters (up to 5000 cycles per minute [CPM]) have been developed. The underlying premise for these ultra-high-speed cutters is that increasing the cut rate reduces the size of the vitreous pieces; and the resulting less viscous gel is more easily aspirated and removed, despite the dramatically reduced diameter of the vitreous cutters.4

Efforts also have been made to improve the duty cycle (DC) of vitreous cutters, particularly at higher cut rates. At high-speed velocity, most conventional cutters decrease their DC, or percent of port open time, throughout the cut cycle; and consequently, there is an expected decrease in the water and vitreous flow rates and a corresponding increase in the surgical time required.5, 6 In most vitrectomy machines, while the aspiration rate and cut rate can be controlled, the DC cannot.

Recently, a new vitrectomy system with dual pneumatic cutters made DC control available. With the introduction of this new variable, different DC settings may be used, affecting the surgical technique and the flow behavior during surgery. The purpose of this study is to determine the performance of ultra-high-speed cutters operated with this variable DC setting.

Analysis of a 23-gauge ultra high-speed cutter with duty cycle control.

The present disclosure described methods, systems, and techniques for applying contrast-enhanced ultrasound to locate areas of blockage within retinal vessels and to break up clots that are causing damage. In addition to identifying the damaged area, the researchers anticipate that the initial image may serve as a baseline for monitoring the effect of treatment on the vessel, which may be achieved in multiple ways. The vibration effect of the ultrasound itself may suffice to dislodge clots. The microbubbles may also be coated or filled with medication, with ultrasonic shock waves activating the coating or causing mini explosions to release the medicine. Loading the microbubbles with a therapeutic agent, visualizing their presence at the diseased site using the ultrasound diagnostic mode, and then activating the microbubbles to release their contents at the targeted lesion could be a powerful and effective way to reverse occlusion without harming other areas of the eye or body.

Ultrasound and microbubbles in ocular diagnostics and therapies

Transcranial near-infrared (NIR) treatment of neurological diseases has gained recent momentum. However, the low NIR dose available to the brain, which shows severe scattering and absorption of the photons by human tissues, largely limits its effectiveness in clinical use. Hereby, we propose to take advantage of the strong scattering effect of the cranial tissues by applying an evenly distributed multiunit emitter array on the scalp to enhance the cerebral photon density while maintaining each single emitter operating under the safe thermal limit. By employing the Monte Carlo method, we simulated the transcranial propagation of the array emitted light and demonstrated markedly enhanced intracranial photon flux as well as improved uniformity of the photon distribution. These enhancements are correlated with the source location, density, and wavelength of light. To the best of our knowledge, we present the first systematic analysis of the intracranial light field established by the scalp-applied multisource array and reveal a strategy for the optimization of the therapeutic effects of the NIR radiation.

https://www.spiedigitallibrary.org/journals/Journal-of-Biomedical-Optics/volume-20/issue-08/088001/Monte-Carlo-analysis-of-the-enhanced-transcranial-penetration-using-distributed/10.1117/1.JBO.20.8.088001.pdf

Monte Carlo analysis of the enhanced transcranial penetration using distributed near-infrared emitter array

Purpose:To determine in vitro effects of a plasma polymerized N-isopropyl acrylamide (pNIPAM) coating for thermally controllable adhesion to retinal tissue.Methods:Polyimide (50 μm), parylene C [poly(monochloro-p-xylylene)] (20 μm), and poly(dimethyl siloxane) (PDMS) (200 μm) coated with pNIPAM were

Mark S. Humayun

Papers

Floating-disk parylene microvalve for self-regulating biomedical flow controls

Analysis of a 23-gauge ultra high-speed cutter with duty cycle control.

Ultrasound and microbubbles in ocular diagnostics and therapies

Monte Carlo analysis of the enhanced transcranial penetration using distributed near-infrared emitter array

Reversible thermosensitive glue for retinal implants.