Design and performance of an ultrahigh vacuum spectroscopic-imaging scanning tunneling microscope with a hybrid vibration isolation system.

A spectroscopic imaging-scanning tunneling microscope (SI-STM) allows for the atomic scale visualization of the surface electronic and magnetic structure of novel quantum materials with a high energy resolution. To achieve the optimal performance, a low vibration facility is required. Here, we describe the design and performance of an ultrahigh vacuum STM system supported by a hybrid vibration isolation system that consists of a pneumatic passive and a piezoelectric active vibration isolation stage. We present the detailed vibrational noise analysis of the hybrid vibration isolation system, which shows that the vibration level can be suppressed below 10-8 m/sec/√Hz for most frequencies up to 100 Hz. Combined with a rigid STM design, vibrational noise can be successfully removed from the tunneling current. We demonstrate the performance of our STM system by taking high resolution spectroscopic maps and topographic images on several quantum materials. Our results establish a new strategy to achieve an effective vibration isolation system for high-resolution STM and other scanning probe microscopies to investigate the nanoscale quantum phenomena.

Spontaneous Spinal Epidural Hematoma After Normal Spontaneous Delivery with Epidural Analgesia: Case Report and Literature Review.

BACKGROUND: Pregnancy is a known risk factor for spontaneous spinal epidural hematoma. During cesarean section or vaginal delivery, the unstable hemodynamic status that may occur owing to fluctuation of intra-abdominal pressure increases the possibility of spontaneous spinal epidural hematoma. During labor and the postpartum period, neurologic symptoms may be masked by labor pain or anesthesia block, which makes early diagnosis difficult, especially in the obstetric clinic without a neurologist or neurosurgeon. CASE DESCRIPTION: A 28-year-old woman who had a normal spontaneous delivery under epidural anesthesia developed bilateral lower limb flaccid paralysis and loss of sensation 12.5 hours after delivery. Magnetic resonance imaging showed a 5.2 × 0.9 × 2 cm spinal epidural hematoma with severe spinal cord stenosis at the T2-T5 level with no evidence of a vascular anomaly. After emergent evacuation of the spinal epidural hematoma, lower limb muscle power improved from 0/5 to 1/5, and sensation gradually returned to bilateral lower limbs 22 days postoperatively. Deep vein thrombosis developed at 35 days postoperatively, and an inferior vena cava filter was implanted with urokinase infusion for thrombolytic therapy. She was discharged on day 52 after admission, and lower limb muscle power returned to normal after 3 months. CONCLUSIONS: Clinicians should observe postpartum women for signs of myelopathy or back tenderness and closely monitor neurologic function until anesthesia has run its course. A prompt diagnosis can enable prompt intervention.

The use of a novel signal analysis to identify the origin of idiopathic right ventricular outflow tract ventricular tachycardia during sinus rhythm: Simultaneous amplitude frequency electrogram transformation mapping.

INTRODUCTION: The signal characteristics of intracardiac bipolar electrograms at the origin of idiopathic RVOT-VT during sinus rhythm remain unclear. OBJECTIVE: The study sought to develop a novel real-time/online technique, simultaneous amplitude frequency electrogram transformation (SAFE-T), to quantify and localize the diseased ventricular substrate in idiopathic RVOT-VT. METHODS: We retrospectively investigated the intracardiac bipolar recordings in 70 consecutive patients (26% male, mean age 42±12 years) who underwent successful radiofrequency catheter ablation of idiopathic RVOT-VT. We quantified the extent of the frequency fraction of ventricular potentials during sinus rhythm or ventricular pacing using a novel formula, the product of instantaneous amplitude and frequency, and showed that in a 3D geometry as an online SAFE-T map. RESULTS: The characteristics of the HHT spectra of electrograms derived from VT origins demonstrated high frequency components (>70 Hz), which were independent of the rhythm. The density of the abnormal potentials at the VT origins were higher (VT origins, 7.5±2.3 sites/cm2 vs. surrounding myocardium, 1.5±1.3 sites/cm2, p<0.001), and were significantly decreased after ablation (0.7±0.6 sites/cm2, p<0.001). A small region of abnormal potentials were observed in the VT origins (mean area of 1.5±0.8 cm2). The SAFE-T maps predicted the VT origins with 92% sensitivity, 78% specificity with optimal cut-off value of >3.0 Hz·mV. CONCLUSION: The online SAFE-T map was feasible for quantifying the diseased ventricular substrate, irrespective of the rhythm of activation, and can be used to identify the optimal ablation targets for idiopathic RVOT-VT. We found a limited region of abnormal potentials where the RVOT-VT origins were successfully ablated.

Anaphylactoid shock induced by oxytocin administration--a case report.

"Piton-S", a preparation of synthetic hormone of oxytocin, is the most common pharmacologic agent used for the induction and augmentation of labor, as well as preventing postpartum hemorrhage owing to its uterotonic properties. There are many adverse effects reported with oxytocin, including hypotension and tachycardia. Anaphylactoid reaction to oxytocin is extremely rare. Here we bring forth a case who sustained from anaphylactoid shock following oxytocin administration during the act of cesarean section. We would like to discuss the proper management of perioperative anaphylaxis after review of similar cases in the literature.