Photonic time-crystals - fundamental concepts [Invited].

Photonic Time-Crystals (PTCs) are materials in which the refractive index varies periodically and abruptly in time. This medium exhibits unusual properties such as momentum bands separated by gaps within which waves can be amplified exponentially, extracting energy from the modulation. This article provides a brief review on the concepts underlying PTCs, formulates the vision and discusses the challenges.

Photonic time crystals: a materials perspective [Invited].

Recent advances in ultrafast, large-modulation photonic materials have opened the door to many new areas of research. One specific example is the exciting prospect of photonic time crystals. In this perspective, we outline the most recent material advances that are promising candidates for photonic time crystals. We discuss their merit in terms of modulation speed and depth. We also investigate the challenges yet to be faced and provide our estimation on possible roads to success.

[NOVEL CONCEPTS AND CHANGES IN TOTAL JOINT ARTHROPLASTY IN THE 21ST CENTURY].

INTRODUCTION: Total joint arthroplasty (TJA) is amongst the most common elective orthopedic surgeries. Since their introduction in 1951 there have been changes not only in prosthesis design and surgical approaches, but also in patient management, anesthesia, drug regimen and robotic arm assistance. These changes led to advancement in patient safety and shorter hospitalization. Today TJA is accessible for a wider age and function range of patients, which has led to an exponential growth in the number of procedures conducted.

Photonic-Crystal Scintillators: Molding the Flow of Light to Enhance X-Ray and γ-Ray Detection.

Scintillators are central for detection of γ-ray, x-ray, and high energy particles in various applications, all seeking higher scintillation yield and rate. However, these are limited by the intrinsic isotropy of spontaneous emission of the scintillation light and its inefficient outcoupling. We propose a new design methodology for scintillators that exploits the Purcell effect to enhance their light emission. As examples, we show 1D photonic crystals from scintillator materials that achieve directional emission and fivefold enhancement in the number of detectable photons per excitation.

Keeping the Finger on the Pulse: Cardiac Arrhythmias in Hand Surgery Using Local Anesthesia with Adrenaline.

BACKGROUND: The wide-awake local anesthesia no tourniquet (WALANT) technique in hand surgery is gaining popularity. The authors aimed to prospectively analyze the frequency and type of arrhythmias in patients undergoing hand surgery under local anesthesia and to examine whether the addition of adrenaline affects their incidence. METHODS: Adult patients undergoing hand surgery under local anesthesia were randomized into two groups: group 1, local anesthesia with lidocaine and tourniquet; and group 2, local anesthesia with lidocaine and adrenaline (WALANT). Patients with a history of arrhythmias were excluded. Patients were connected to Holter electrocardiographic monitoring before surgery and up until discharge. The records were blindly compared between the groups regarding types of arrhythmias, and frequency and timing relative to injection and tourniquet inflation. RESULTS: One hundred two patients were included between August of 2018 and August of 2019 (age, 59.7 ± 13.6 years; 71 percent women; 51 in each group). No major arrhythmia (ventricular tachycardia, ventricular fibrillation, atrial fibrillation) or arrhythmia-related symptoms were recorded for either group. Minor arrhythmias (including atrial premature beats, ventricular premature beats, and atrial tachycardia) were recorded in 68 patients (66.6 percent), with no statistical difference between the groups. There were three patients with minor arrhythmias during inflation of the tourniquet. Patients in the adrenaline group had 2 percent sinus tachycardia during injection and 4 percent asymptomatic bradyarrhythmias. These findings do not require any further treatment. CONCLUSIONS: The authors' results show that hand operations using WALANT technique in patients with no history of arrhythmia are safe and are not arrhythmogenic; therefore, there is no need for routine perioperative continuous electrocardiographic monitoring. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.