Extending Quantum Coherence in Diamond

We experimentally demonstrate over two orders of magnitude increase in the coherence time of nitrogen vacancy centres in diamond by implementing decoupling techniques. We show that equal pulse spacing decoupling performs just as well as non-periodic Uhrig decoupling and has the additional benefit that it allows us to take advantage of "revivals" in the echo (due to the coherent nature of the bath) to explore the longest coherence times. At short times, we can extend the coherence of particular quantum states out from T_2*=2.7 us out to an effective T_2 > 340 us. For preserving arbitrary states we show the experimental importance of using pulse sequences, that through judicious choice of the phase of the pulses, compensate the imperfections of individual pulses for all input states. At longer times we use these compensated sequences to enhance the echo revivals and show a coherence time of over 1.6 ms in ultra-pure natural abundance 13C diamond.Comment: 7 pages, 7 figures; minor syntax/typo. changes and updated reference

New State Record and Notable Range Extension for \u3ci\u3eLibellula Semifasciata\u3c/i\u3e (Odonata: Libellulidae)

The painted skimmer, Libellula semifasciata Burmeister (Odonata: Libellulidae), is an eastern species of dragonfly that has never been documented in Iowa. In this note we report two observations and the collection of a voucher for this species in southeast Iowa in the last three years. Based on other records of this species, including those from neighboring states and more northerly latitudes, we propose that these observations are evidence of a range extension

Limits on violations of Lorentz Symmetry from Gravity Probe B

Generic violations of Lorentz symmetry can be described by an effective field theory framework that contains both general relativity and the standard model of particle physics called the Standard-Model Extension (SME). We obtain new constraints on the gravitational sector of the SME using recently published final results from Gravity Probe B. These include for the first time an upper limit at the 10^(-3) level on the time-time component of the new tensor field responsible for inducing local Lorentz violation in the theory, and an independent limit at the 10^(-7) level on a combination of components of this tensor field.Comment: 8 pages, 1 figur

Development of explosive welding techniques for fabrication of regeneratively cooled thrust chambers for large rocket engine requirements Final report, 28 Jun. 1967 - 15 Sep. 1970

Explosive welding techniques in fabricating regeneratively cooled thrust chambers for large rocket engine requirements including ultrasonic inspection, metallography, and burst testin

Association Between Air Pollution and Low Birth Weight: A Community-Based Study

The relationship between maternal exposure to air pollution during periods of pregnancy (entire and specific periods) and birth weight was investigated in a well-defined cohort. Between 1988 and 1991, all pregnant women living in four residential areas of Beijing were registered and followed from early pregnancy until delivery. Information on individual mothers and infants was collected. Daily air pollution data were obtained independently. The sample for analysis included 74,671 first-parity live births were gestational age 37-44 weeks. Multiple linear regression and logistic regression were used to estimate the effects of air pollution on birth weight and low birth weight (< 2,500 g), adjusting for gestational age, residence, year of birth, maternal age, and infant gender. There was a significant exposure-response relationship between maternal exposures to sulfur dioxide (SO2) and total suspended particles (TSP) during the third trimester of pregnancy and infant birth weight. The adjusted odds ratio for low birth weight was 1.11 (95% CI, 1.06-1.16) for each 100 micrograms/m3 increase in SO2 and 1.10 (95% CI, 1.05-1.14) for each 100 micrograms/m3 increase in TSP. The estimated reduction in birth weight was 7.3 g and 6.9 g for each 100 micrograms/m3 increase in SO2 and in TSP, respectively. The birth weight distribution of the high-exposure group was more skewed toward the left tail (i.e., with higher proportion of births < 2,500 g) than that of the low-exposure group. Although the effects of other unmeasured risk factors cannot be excluded with certainty, our data suggests that TSP and SO2, or a more complex pollution mixture associated with these pollutants, contribute to an excess risk of low birth weight in the Beijing population.National Institute of Environmental Health Sciences (ES05947, ES08337); National Institute of Child Health & Human Development (R01 HD32505); Department of Health and Human Services (MCJ-259501, HRSA 5 T32 PE10014

Experiences With Chiropractic Care for Patients With Low Back or Neck Pain.

BackgroundMusculoskeletal disorders are the second leading cause of disability worldwide.ObjectiveExamine experiences of chiropractic patients in the United States with chronic low back or neck pain.MethodObservational study of 1853 chronic low back pain and neck pain patients (74% female) who completed an online questionnaire at the 3-month follow-up that included Consumer Assessment of Healthcare Providers and Systems (CAHPS) items assessing their experiences with care.ResultsWe found similar reports of communication for the chiropractic sample and patients in the 2016 CAHPS National Database, but 85% in the database versus 79% in the chiropractic sample gave the most positive response to the time spent with provider item. More patients in the CAHPS database rated their provider at the top of the scale (8 percentage points). More chiropractic patients reported always getting answers to questions the same day (16 percentage points) and always being seen within 15 minutes of their appointment time (29 percentage points).ConclusionsThe positive experiences of patients with chronic back and neck pain are supportive of their use of chiropractic care

Controlling Singlet Fission with Coordination Chemistry-Induced Assembly of Dipyridyl Pyrrole Bipentacenes

Singlet fission has the potential to surpass current efficiency limits in next-generation photovoltaics and to find use in quantum information science. Despite the demonstration of singlet fission in various materials, there is still a great need for fundamental design principles that allow for tuning of photophysical parameters, including the rate of fission and triplet lifetimes. Here, we describe the synthesis and photophysical characterization of a novel bipentacene dipyridyl pyrrole (HDPP-Pent) and its Li- and K-coordinated derivatives. HDPP-Pent undergoes singlet fission at roughly 50% efficiency (τ_(SF) = 730 ps), whereas coordination in the Li complex induces significant structural changes to generate a dimer, resulting in a 7-fold rate increase (τ_(SF) = 100 ps) and more efficient singlet fission with virtually no sacrifice in triplet lifetime. We thus illustrate novel design principles to produce favorable singlet fission properties, wherein through-space control can be achieved via coordination chemistry-induced multipentacene assembly