Coherent radiation at visible wavelengths from sub-keV electron beams.

The Smith-Purcell effect allows for coherent free-electron-driven compact light sources over the entire electromagnetic spectrum. Intriguing interaction regimes, with prospects for quantum optical applications, are expected when the driving free electron enters the sub-keV range, though this has until now remained an experimental challenge. Here, we demonstrate the Smith-Purcell light emission from UV to visible using engineerable, fabricated gratings with periodicities as low as 19 nm and with electron energies as low as 300 eV.

Ketoacidosis in a Patient with Type 2 Diabetes Requiring Alpelisib: Learnings and Observations Regarding Alpelisib Initiation and Rechallenge.

Background: Diabetic ketoacidosis (DKA) is a rare complication of alpelisib, but cases of DKA are reported. Alpelisib's safety in patients with long-standing, suboptimally controlled diabetes is unclear since clinical trials of alpelisib did not include them.

Case: A case is presented on a patient with metastatic breast cancer and type 2 diabetes admitted for DKA eleven days after starting alpelisib.

Cylindrical Metalens for Generation and Focusing of Free-Electron Radiation.

Metasurfaces constitute a powerful approach to generate and control light by engineering optical material properties at the subwavelength scale. Recently, this concept was applied to manipulate free-electron radiation phenomena, rendering versatile light sources with unique functionalities. In this Letter, we experimentally demonstrate spectral and angular control over coherent light emission by metasurfaces that interact with free-electrons under grazing incidence.

Shaping of Electron Beams Using Sculpted Thin Films.

Electron beam shaping by sculpted thin films relies on electron-matter interactions and the wave nature of electrons. It can be used to study physical phenomena of special electron beams and to develop technological applications in electron microscopy that offer new and improved measurement techniques and increased resolution in different imaging modes. In this Perspective, we review recent applications of sculpted thin films for electron orbital angular momentum sorting, improvements in phase contrast transmission electron microscopy, and aberration correction.

Effects of 'rescue' dose of antenatal corticosteroids on placental histopathology in preterm births.

Introduction: Antenatal corticosteroids (ACS) are frequently used to reduce neonatal morbidity in preterm births (PTBs). A 'rescue' dose of ACS can be administer, if the risk of PTB remains. Some reports indicated that repeated doses of ACS might impact placental histology and possibly its function.