44 research outputs found
Paper Session II-A - Space Station Requirements and Transportation Options for Lunar Outpost
The 1990\u27s and Space Station Freedom are the next critical, steps in our space endeavors which will be stepping stones for the new century permanent exploration of the moon and the solar system. Freedom Station and transportation requirements for the lunar outpost are partitioned into three phases - the emplacement phase, the consolidation phase, and the utilization phase. The Earth-to-orbit transportation system must ferry vehicles, cargo, crew, and propellant to low Earth orbit (LEO) to support these lunar outpost phase requirements. The lunar transportation system is designed to move crew, science instruments, and support equipment from LEO to the surface of the moon. The lunar transportation system consists of the lunar transfer vehicle (LTV) and the lunar excursion vehicle (LEV). These reusable and highly reliable vehicles provide multiple mission utility through common vehicle usage for cargo and crew delivery. Mission analyses and the lunar payload model have established vehicle design and sizing requirements. A 300-km circular orbit is assumed for the low lunar orbit (LLO) staging point for the lunar surface base. Freedom is used as the LEO transportation node. The LEV is sized to deliver 15t to the lunar surface for the first piloted flight. The LEV can deliver 33t to the lunar surface in the cargo expendable mode. Different transportation system options are designed and sized to compare and show sensitivity of the initial mass required in LEO to determine the most effective and efficient transportation concept
Haptoglobin phenotype and abnormal uterine artery Doppler in a racially diverse cohort
The anti-oxidant and proangiogenic protein haptoglobin (Hp) is believed to be important for implantation and pregnancy, although its specific role is not known. The three phenotypes (1-1, 2-1 and 2-2) differ in structure and function. Hp 2-2 is associated with increased vascular stiffness in other populations. We examined whether Hp phenotype is associated with abnormal uterine artery Doppler (UAD) in pregnancy
Increasing Maternal Body Mass Index and Characteristics of the Second Stage of Labor
To evaluate the length of the second stage of labor in relation to increasing maternal prepregnancy BMI among nulliparous parturients, and to determine whether route of delivery differs among obese, overweight, and normal weight women reaching the second stage
Pregnancy Outcomes With Weight Gain Above or Below the 2009 Institute of Medicine Guidelines
To evaluate pregnancy outcomes according to 2009 Institute of Medicine (IOM) gestational weight gain guidelines
First-Trimester Prediction of Preeclampsia in Nulliparous Women at Low Risk
To identify clinical characteristics and biochemical markers in first-trimester samples that would possibly predict the subsequent development of preeclampsia
VITAMIN C AND E SUPPLEMENTATION TO PREVENT SPONTANEOUS PRETERM BIRTH
Evidence suggests an association between maternal vitamin C levels and preterm premature rupture of membranes (PROM) or preterm labor. The objective of this study was to estimate whether maternally administered vitamins C and E lowers the risk of spontaneous preterm birth (SPB)
The Utility of Uterine Artery Doppler Velocimetry in Prediction of Preeclampsia in a Low-Risk Population:
The underlying pathophysiology of preeclampsia is thought to be abnormal trophoblast invasion of the spiral arteries, leading to maldevelopment of uteroplacental perfusion. We estimated whether uterine artery Doppler measurements made in the early second trimester would predict the subsequent development of preeclampsia
Vitamins C and E to Prevent Complications of Pregnancy-Associated Hypertension
Oxidative stress has been proposed as a mechanism linking the poor placental perfusion characteristic of preeclampsia with the clinical manifestations of the disorder. We assessed the effects of antioxidant supplementation with vitamins C and E, initiated early in pregnancy, on the risk of serious adverse maternal, fetal, and neonatal outcomes related to pregnancy-associated hypertension
Author Correction: Super-resolved time–frequency measurements of coupled phonon dynamics in a 2D quantum material
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Super-resolved time–frequency measurements of coupled phonon dynamics in a 2D quantum material
Methods to probe and understand the dynamic response of materials following impulsive excitation are important for many fields, from materials and energy sciences to chemical and neuroscience. To design more efficient nano, energy, and quantum devices, new methods are needed to uncover the dominant excitations and reaction pathways. In this work, we implement a newly-developed superlet transform—a super-resolution time-frequency analytical method—to analyze and extract phonon dynamics in a laser-excited two-dimensional (2D) quantum material. This quasi-2D system, 1T-TaSe2, supports both equilibrium and metastable light-induced charge density wave (CDW) phases mediated by strongly coupled phonons. We compare the effectiveness of the superlet transform to standard time-frequency techniques. We find that the superlet transform is superior in both time and frequency resolution, and use it to observe and validate novel physics. In particular, we show fluence-dependent changes in the coupled dynamics of three phonon modes that are similar in frequency, including the CDW amplitude mode, that clearly demonstrate a change in the dominant charge-phonon couplings. More interestingly, the frequencies of the three phonon modes, including the strongly-coupled CDW amplitude mode, remain time- and fluence-independent, which is unusual compared to previously investigated materials. Our study opens a new avenue for capturing the coherent evolution and couplings of strongly-coupled materials and quantum systems