Precise Determination of Proton Spin-Precession Angles in the K600 Spectrometer and Beamline

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

ISO Spectroscopy of Young Stellar Objects

Observations of gas-phase and solid-state species toward young stellar objects (YSOs) with the spectrometers on board the Infrared Space Observatory are reviewed. The excitation and abundances of the atoms and molecules are sensitive to the changing physical conditions during star-formation. In the cold outer envelopes around YSOs, interstellar ices contain a significant fraction of the heavy element abundances, in particular oxygen. Different ice phases can be distinguished, and evidence is found for heating and segregation of the ices in more evolved objects. The inner warm envelopes around YSOs are probed through absorption and emission of gas-phase molecules, including CO, CO_2, CH_4 and H_2O. An overview of the wealth of observations on gas-phase H_2O in star-forming regions is presented. Gas/solid ratios are determined, which provide information on the importance of gas-grain chemistry and high temperature gas-phase reactions. The line ratios of molecules such as H_2, CO and H_2O are powerful probes to constrain the physical parameters of the gas. Together with atomic and ionic lines such as [0 I] 63 µm, [S I] 25 µm and (Si II] 35 µm, they can also be used to distinguish between photon- and shock-heated gas. Finally, spectroscopic data on circumstellar disks around young stars are mentioned. The results are discussed in the context of the physical and chemical evolution of YSOs

A Complete Set of In-plane Spin-transfer Coefficients for Small Angle pp Elastic Scattering at 200 MeV

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Preparation of water-free silica-based optical-fibre waveguide

A technique is described, whereby the hydroxyl absorption bands of the new phosphosilicate-core optical-fibre waveguide, which arise from impurities in the cladding, can be largely eliminated. The resulting fibre has ultralow loss over the entire wavelength range 0.4-1.1µm

New silica-based low-loss optical fibre

A new type of silica-based optical fibre has been made from relatively cheap and abundant materials. The attenuation is very low over the entire range from the near ultraviolet to the gallium-arsenide-laser wavelength. The minimum loss of 2.7 dB/km occurs at 0.83µm

Birth outcomes among adolescent and young adult cancer survivors

IMPORTANCE: Cancer diagnosis and treatment may adversely affect reproductive outcomes among female cancer survivors. OBJECTIVE: To compare the birth outcomes of adolescent and young adult cancer survivors (AYA [diagnosed at ages 15-39 years]) with those of women without a cancer diagnosis. DESIGN, SETTING, AND PARTICIPANTS: The North Carolina Central Cancer Registry (CCR) was used to identify female AYA cancer survivors diagnosed from January 2000 to December 2013; CCR records were linked to statewide birth certificate files from January 2000 to December 2014 to identify postdiagnosis live births to AYA survivors (n = 2598). A comparison cohort of births to women without a recorded cancer diagnosis was randomly selected from birth certificate files (n = 12 990) with frequency matching on maternal age and year of delivery. MAIN OUTCOMES AND MEASURES: Prevalence of preterm birth, low birth weight, small-for-gestational-age births, cesarean delivery, and low Apgar score. RESULTS: Overall, 2598 births to AYA cancer survivors (mean [SD] maternal age, 31 [5] years) were included. Births to AYA cancer survivors had a significantly increased prevalence of preterm birth (prevalence ratio [PR], 1.52; 95% CI, 1.34-1.71), low birth weight (PR, 1.59; 95% CI, 1.38-1.83), and cesarean delivery (PR, 1.08; 95% CI, 1.01-1.14) relative to the comparison cohort of 1299. The higher prevalence of these outcomes was most concentrated among births to women diagnosed during pregnancy. Other factors associated with preterm birth and low birth weight included treatment with chemotherapy and a diagnosis of breast cancer, non-Hodgkin lymphoma, or gynecologic cancers. The prevalence of small-for-gestational-age births and low Apgar score (<7) did not differ significantly between groups. CONCLUSIONS AND RELEVANCE: Live births to AYA cancer survivors may have an increased risk of preterm birth and low birth weight, suggesting that additional surveillance of pregnancies in this population is warranted. Our findings may inform the reproductive counseling of female AYA cancer survivors

Pairing of fermions in atomic traps and nuclei

Pairing gaps for fermionic atoms in harmonic oscillator traps are calculated for a wide range of interaction strengths and particle number, and compared to pairing in nuclei. Especially systems, where the pairing gap exceeds the level spacing but is smaller than the shell splitting $\hbar\omega$, are studied which applies to most trapped Fermi atomic systems as well as to finite nuclei. When solving the gap equation for a large trap with such multi-level pairing, one finds that the matrix elements between nearby harmonic oscillator levels and the quasi-particle energies lead to a double logarithm of the gap, and a pronounced shell structure at magic numbers. It is argued that neutron and proton pairing in nuclei belongs to the class of multi-level pairing, that their shell structure follows naturally and that the gaps scale as $\sim A^{-1/3}$ - all in qualitative agreement with odd-even staggering of nuclear binding energies. Pairing in large systems are related to that in the bulk limit. For large nuclei the neutron and proton superfluid gaps approach the asymptotic value in infinite nuclear matter: $\Delta\simeq 1.1$ MeV.Comment: 11 pages, 5 figure

Effect of Nuclear Quadrupole Interaction on the Relaxation in Amorphous Solids

Recently it has been experimentally demonstrated that certain glasses display an unexpected magnetic field dependence of the dielectric constant. In particular, the echo technique experiments have shown that the echo amplitude depends on the magnetic field. The analysis of these experiments results in the conclusion that the effect seems to be related to the nuclear degrees of freedom of tunneling systems. The interactions of a nuclear quadrupole electrical moment with the crystal field and of a nuclear magnetic moment with magnetic field transform the two-level tunneling systems inherent in amorphous dielectrics into many-level tunneling systems. The fact that these features show up at temperatures $T<100mK$, where the properties of amorphous materials are governed by the long-range $R^{-3}$ interaction between tunneling systems, suggests that this interaction is responsible for the magnetic field dependent relaxation. We have developed a theory of many-body relaxation in an ensemble of interacting many-level tunneling systems and show that the relaxation rate is controlled by the magnetic field. The results obtained correlate with the available experimental data. Our approach strongly supports the idea that the nuclear quadrupole interaction is just the key for understanding the unusual behavior of glasses in a magnetic field.Comment: 18 pages, 9 figure