A Cold-Strontium Laser in the Superradiant Crossover Regime

Recent proposals suggest that lasers based on narrow dipole-forbidden transitions in cold alkaline earth atoms could achieve linewidths that are orders of magnitude smaller than linewidths of any existing lasers. Here, we demonstrate a laser based on the 7.5 kHz linewidth dipole forbidden $^3$P$_1$ to $^1$S$_0$ transition in laser-cooled and tightly confined $^{88}$Sr. We can operate this laser in the bad-cavity regime, where coherence is primarily stored in the atoms, or continuously tune to the more conventional good-cavity regime, where coherence is primarily stored in the light field. We show that the cold-atom gain medium can be repumped to achieve quasi steady-state lasing, and demonstrate up to an order of magnitude suppression in the sensitivity of laser frequency to changes in cavity length, the primary limitation for the most frequency stable lasers today.Comment: 5 pages, 4 figure

Following the relaxation dynamics of photoexcited aniline in the 273-266 nm region using time-resolved photoelectron imaging

Scanning tunnelling microscopy (STM) and Auger electron spectroscopy (AES) have been used to investigate the growth morphology of ultra-thin Pb films on the Ni3Al(111) face at room temperature. A previous study [K. Miśków and A. Krupski Appl Surf Sci 273, 2013, 554] using low-energy electron diffraction (LEED) and real time Auger intensity recording has demonstrated that an initial two-dimensional growth of the first Pb monolayer thick ‘wetting layer’ takes place. With further deposition and for T = 300 K, flat three atomic-layer-high islands are grown. Above 350 K, the Stranski–Krastanov growth mode was observed. In the current study, the analysis of STM measurements indicate and confirm that for coverage θ = 1.0 ML two-dimensional growth of the first Pb monolayer took place. Above θ > 1.0 ML, a three-dimensional growth of the Pb islands was observed with a strongly preferred atomic-scale ‘magic height (N),’ hexagonal shape and flat-tops. At coverage θ = 3.5 ML, only islands containing N = 3, 5, 7 and 11 atomic layers of Pb are observed. At the higher coverage θ = 5.5 ML, three types of regular hexagonal islands with side lengths of 25, 30 and 45 nm are observed. Furthermore, three different island adsorption configurations rotated by 10° ± 1° and 30° ± 6° with respect to each other were observed. After an annealing at T = 400 K of 5.5 ML of lead deposited at RT on the Ni3Al(111) the morphology of the surface changes. Post-anneal, islands of Pb are observed above the ‘wetting layer’ with an estimated average size and diameter of 768 ± 291 nm2 and 38.17 ± 6.56 nm and constant uniform height of two atomic layers (N = 2)

An evaluation of whether a gestational weight gain of 5 to 9 kg for obese women optimizes maternal and neonatal health risks

Background Maternal obesity has a wide range of health effects on both the pregnant woman and developing fetus. The clinical significance of these disorders, combined with a dramatically increasing prevalence of obesity among pregnant women has precipitated a major health crisis in the United States. The most commonly used recommendations for gestational weight gain were established by the Institute of Medicine (IOM) in 2009 and have become well known and often adopted. The authors of the IOM report acknowledged that the recommended gestational weight gain of 5 to 9 kg for obese women whose body mass index was greater than 30 kg/m2 was based on very little empirical evidence. The objective of this study was to evaluate whether a 5 to 9 kg weight gain, for obese women, optimized a set of maternal and neonatal health outcomes. Methods Data containing approximately 12,000,000 birth records were obtained from the United States Natality database for the years 2014 to 2016. A Bayesian modeling approach was used to estimate the controlled direct effects of pre-pregnancy body mass index and gestational weight gain. Results Obese women gaining less than 5 kg during pregnancy had reduced maternal risks for gestational hypertension, eclampsia, induction of labor and Caesarian section. In contrast, maternal gestational weight gain of less than 5 kg was associated with increased risks for multiple adverse neonatal outcomes with macrosomia the exception. Obese women who gained more than 9 kg during pregnancy had increased risk for multiple maternal and neonatal adverse outcomes. Conclusions Obese women who were observed to gain less than 5 kg during gestation had reduced odds of several peripartum disorders. However, this lower gestational weight gain was associated with an increase in multiple risks for the neonate

Instructional Technology Integration and Situational Interest in Math

Motivating students to be engaged in learning, especially in math, has been a perennial challenge for educators. Over the past 20 years, instructional technology has become an increasingly prevalent teaching tool that, according to many educational observers and researchers, can have a transformative effect on teaching and learning because of the way that it engages today’s students. The purpose of this quantitative study was to determine the relationship between students’ perceptions of technology integration and situational interest in middle school math so that educational planners will be better informed when making instructional decisions concerning the use of technology in the math classroom. In this study, the relationship between students’ perceptions of teacher technology integration and situational interest in math was investigated using the Pearson product-moment correlation coefficient. A moderate, positive correlation was established and found to be significant [r=.461, n=223, pResults from this study showed middle school students who perceive a higher degree of teacher instructional technology integration show higher levels of situational interest in math. Results also indicated that there was a statistically significant difference in the relationship between perceptions of instructional technology integration and situational interest in math between sixth and eighth graders. No statistically significant differences in this relationship were found between any other sub-groups. The findings of this study suggest that instructional technology can be a motivating factor for middle school students regardless of sex, grade, or race and that educators should pursue student centered paths to instructional technology integration