Measurement of Dynamics in Strontlum Magnetc-Optical Trap

Summary form only given. The experiment consists of a Sr vapor cell magneto optical trap (MOT). Since for laser-cooled alkaline earth atoms the even isotopes have no hyperfine structure, they provide an ideal system for testing Doppler-cooling theory. (Alkali atoms are subject to sub-Doppler cooling mechanisms.) We have measured the spring constant (k) and damping coefficient (/spl alpha/) in a strontium MOT by observing the damped oscillation response of the trapped atom location to a square-wave chopped pushing beam

Cooling and Trapping of Atomic Strontium

We present a detailed investigation of strontium magneto-optical trap (MOT) dynamics. Relevant physical quantities in the trap, such as temperature, atom number and density, and loss channels and lifetime, are explored with respect to various trap parameters. By studying the oscillatory response of a two-level 1S0–1P1 88Sr MOT, we firmly establish the laser cooling dynamics predicted by Doppler theory. Measurements of the MOT temperature, however, deviate severely from Doppler theory predictions, implying significant additional heating mechanisms. To explore the feasibility of attaining quantum degenerate alkaline-earth samples via evaporative cooling, we also present the first experimental demonstration of magnetically trapped metastable 88Sr. Furthermore, motivated by the goal of establishing the fermionic isotope 87Sr as one of the highest-quality, neutral-atom-based optical frequency standards, we present a preliminary study of sub-Doppler cooling in a 87Sr MOT. A dual-isotope (87Sr and 88Sr) MOT is also demonstrated

Dynamics in a Two-Level Atom Magneto-Optical Trap

Alkaline-earth-metal atoms present an ideal platform for exploring magneto-optic trap (MOT) dynamics, enabling unique and definitive tests of laser cooling and trapping mechanisms. We have measured the trapping beam intensity, detuning, magnetic-field gradient, trap density, and lifetime dependence of the spring constant κ and damping coefficient α for a 1S0−1P1 88Sr MOT by fitting the oscillatory response of the atom cloud to a step-function force. We find that the observed behavior of κ and α provide a unified and consistent picture of trap dynamics that agrees with Doppler cooling theory at the level of 10%.Additionally, we demonstrate that the trapped atom temperature can be determined directly from measured value of κ and the trap size, in excellent agreement with free-expansion temperature measurements. However, the experimentally determined temperature is much higher than Doppler cooling theory, implying significant additional heating mechanisms

Single-Stage Sub-Doppler Cooling of Alkaline Earth Atoms

We report the first experimental study of sub-Doppler cooling in alkaline earth atoms (87Sr) enabled by the presence of nuclear spin-originated magnetic degeneracy in the atomic ground state. Sub-Doppler cooling in a σ+-σ− configuration is achieved despite the presence of multiple, closely spaced excited states. This surprising result is confirmed by an expanded multilevel theory of the radiative cooling force. Detailed investigations of system performance have shed new insights into (σ+-σ−) cooling dynamics and will likely play an important role in the future development of neutral atom-based optical frequency standards

Development and validation of a visualized prediction model for early miscarriage risk in patients undergoing IVF/ICSI procedures: a real-world multi-center study

BackgroundThis study focuses on the risk of early miscarriage in patients undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). These patients commonly experience heightened stress levels and may discontinue treatment due to emotional burdens associated with repeated failures. Despite the identification of numerous potential factors contributing to early miscarriage, there exists a research gap in integrating these factors into predictive models specifically for IVF/ICSI patients. The objective of this study is to develop a user-friendly nomogram that incorporates relevant risk factors to predict early miscarriage in IVF/ICSI patients. Through internal and external validation, the nomogram facilitates early identification of high-risk patients, supporting clinicians in making informed decisions.MethodsA retrospective analysis was conducted on 20,322 first cycles out of 31,307 for IVF/ICSI treatment at Sun Yat-sen Memorial Hospital between January 2011 and December 2020. After excluding ineligible cycles, 6,724 first fresh cycles were included and randomly divided into a training dataset (n = 4,516) and an internal validation dataset (n = 2,208). An external dataset (n = 1,179) from another hospital was used for validation. Logistic and LASSO regression models identified risk factors, and a multivariable logistic regression constructed the nomogram. Model performance was evaluated using AUC, calibration curves, and decision curve analysis (DCA).ResultsSignificant risk factors for early miscarriage were identified, including female age, BMI, number of spontaneous abortions, number of induced abortions and medical abortions, basal FSH levels, endometrial thickness on hCG day, and number of good quality embryos. The predictive nomogram demonstrated good fit and discriminatory power, with AUC values of 0.660, 0.640, and 0.615 for the training, internal validation, and external validation datasets, respectively. Calibration curves showed good consistency with actual outcomes, and DCA confirmed the clinical usefulness. Subgroup analysis revealed variations; for the elder subgroup (age ≥35 years), female age, basal FSH levels, and number of available embryos were significant risk factors, while for the younger subgroup (age <35 years), female age, BMI, number of spontaneous abortions, and number of good quality embryos were significant.ConclusionsOur study provides valuable insights into the impact factors of early miscarriage in both the general study population and specific age subgroups, offering practical recommendations for clinical practitioners. We have taken into account the significance of population differences and regional variations, ensuring the adaptability and relevance of our model across diverse populations. The user-friendly visualization of results and subgroup analysis further enhance the applicability and value of our research. These findings have significant implications for informed decision-making, allowing for individualized treatment strategies and the optimization of outcomes in IVF/ICSI patients

A Quantum Scattering Interferometer

The collision of two ultra-cold atoms results in a quantum-mechanical superposition of two outcomes: each atom continues without scattering and each atom scatters as a spherically outgoing wave with an s-wave phase shift. The magnitude of the s-wave phase shift depends very sensitively on the interaction between the atoms. Quantum scattering and the underlying phase shifts are vitally important in many areas of contemporary atomic physics, including Bose-Einstein condensates, degenerate Fermi gases, frequency shifts in atomic clocks, and magnetically-tuned Feshbach resonances. Precise measurements of quantum scattering phase shifts have not been possible until now because, in scattering experiments, the number of scattered atoms depends on the s-wave phase shifts as well as the atomic density, which cannot be measured precisely. Here we demonstrate a fundamentally new type of scattering experiment that interferometrically detects the quantum scattering phase shifts of individual atoms. By performing an atomic clock measurement using only the scattered part of each atom, we directly and precisely measure the difference of the s-wave phase shifts for the two clock states in a density independent manner. Our method will give the most direct and precise measurements of ultracold atom-atom interactions and will place stringent limits on the time variations of fundamental constants.Comment: Corrected formatting and typo

Trans-arterial positive ICG staining-guided laparoscopic liver watershed resection for hepatocellular carcinoma

IntroductionAnatomical liver resection is the optimal treatment for patients with resectable hepatocellular carcinoma (HCC). Laparoscopic Couinaud liver segment resection could be performed easily as liver segments could be stained by ultrasound-guided indocyanine green (ICG) injection into the corresponding segment portal vein. Several smaller liver anatomical units (liver watersheds) have been identified (such as S8v, S8d, S4a, and S4b). However, since portal veins of liver watersheds are too thin to be identified under ultrasound, the boundaries of these liver watersheds could not be stained intraoperatively, making laparoscopic resection of these liver watersheds demanding. Digital subtraction angiography (DSA) could identify arteries of liver watersheds with a diameter of less than 2 mm. Yet, its usage for liver watershed staining has not been explored so far.PurposeThe aim of this study is to explore the possibility of positive liver watershed staining via trans-arterial ICG injection under DSA examination for navigating laparoscopic watershed-oriented hepatic resection.MethodsWe describe, in a step-by-step approach, the application of trans-arterial ICG injection to stain aimed liver watershed during laparoscopic anatomical hepatectomy. The efficiency and safety of the technique are illustrated and discussed in comparison with the laparoscopic anatomical liver resection via ultrasound-guided liver segment staining.ResultsEight of 10 HCC patients received successful trans-arterial liver watershed staining. The success rate of the trans-artery staining approach was 80%, higher than that of the ultrasound-guided portal vein staining approach (60%). Longer surgical duration was found in patients who underwent the trans-artery staining approach (305.3 ± 23.2 min vs. 268.4 ± 34.7 min in patients who underwent the ultrasound-guided portal vein staining approach, p = 0.004). No significant difference was found in major morbidity, reoperation rate, hospital stay duration, and 30-day and 90-day mortality between the 2 groups.ConclusionsTrans-arterial ICG staining is safe and feasible for staining the aimed liver watershed, navigating watershed-oriented hepatic resection under fluorescence laparoscopy for surgeons