Order-Unity 13C Nuclear Polarization of [1-13C]Pyruvate in Seconds and the Interplay of Water and SABRE Enhancement

Signal Amplification By Reversible Exchange in SHield Enabled Alignment Transfer (SABRE-SHEATH) is investigated to achieve rapid hyperpolarization of ¹³C₁ spins of [1-¹³C]pyruvate, using parahydrogen as the source of nuclear spin order. Pyruvate exchange with an iridium polarization transfer complex can be modulated via a sensitive interplay between temperature and co-ligation of DMSO and H₂O. Order-unity ¹³C (>50 %) polarization of catalyst-bound [1-¹³C]pyruvate is achieved in less than 30 s by restricting the chemical exchange of [1-¹³C]pyruvate at lower temperatures. On the catalyst bound pyruvate, 39 % polarization is measured using a 1.4 T NMR spectrometer, and extrapolated to >50 % at the end of build-up in situ. The highest measured polarization of a 30-mM pyruvate sample, including free and bound pyruvate is 13 % when using 20 mM DMSO and 0.5 M water in CD₃OD. Efficient ¹³C polarization is also enabled by favorable relaxation dynamics in sub-microtesla magnetic fields, as indicated by fast polarization buildup rates compared to the T₁ spin-relaxation rates (e. g., ∼0.2 s⁻¹ versus ∼0.1 s⁻¹, respectively, for a 6 mM catalyst-[1-¹³C]pyruvate sample). Finally, the catalyst-bound hyperpolarized [1-¹³C]pyruvate can be released rapidly by cycling the temperature and/or by optimizing the amount of water, paving the way to future biomedical applications of hyperpolarized [1-¹³C]pyruvate produced via comparatively fast and simple SABRE-SHEATH-based approaches.     

Slow-light fourier transform interferometer

We describe a new type of Fourier transform (FT) interferometer in which the tunable optical delay between the two arms is realized by using a continuously variable slow-light medium instead of a moving arm as in a conventional setup. The spectral resolution of such a FT interferometer exceeds that of a conventional setup of comparable size by a factor equal to the maximum group index of the slow-light medium. The scheme is experimentally demonstrated by using a rubidium atomic vapor cell as the tunable slow-light medium, and the spectral resolution is enhanced by a factor of approximately 100.     

Observation of B-->eta'K* and evidence for B+-->eta'rho+

We present an observation of B-->eta'K*. The data sample corresponds to 232x10(6) BB[over ] pairs collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center. We measure the branching fractions (in units of 10(-6)) B(B(0)-->eta'K*0)=3.8+/-1.1+/-0.5 and B(B+-->eta'K*+)=4.9(1.7)(+1.9)+/-0.8, where the first error is statistical and the second systematic. A simultaneous fit results in the observation of B-->eta'K* with B(B-->eta'K*)=4.1(-0.9)(+1.0)+/-0.5. We also search for B-->eta'rho and eta'f(0)(980)(f(0)-->pi+pi-) with results and 90% confidence level upper limits B(B+-->eta'rho+)=8.7(-2.8-1.3)(+3.1+2.3) (<14), B(B(0)-->eta'rho0)<3.7, and B(B(0)-->eta'f(0)(980)(f(0)-->pi+pi-))<1.5. Charge asymmetries in the channels with significant yields are consistent with zero.     

Liquid chromatography tandem mass spectrometry determination of free and conjugated estrogens in breast cancer patients before and after exemestane treatment

We report liquid chromatographic separation with tandem mass spectrometry determination of 12 endogenous estrogens and their intact conjugates in blood and urine and its application to study effects of exemestane treatment on estrogen generation and metabolism in postmenopausal women with estrogen-dependent breast cancer. A 0.5 mL aliquot of each urine or serum sample is fractionated with solid phase extraction to a fraction of free estrogen and another fraction of their conjugates. The reversed phase LC/MS/MS determines dansylated estrogens with positive ionization and intact conjugates with negative ionization. The method provides reproducible separation and limit of detection as low as 1 pg mL⁻¹ for free estrogens and 0.03 ng mg⁻¹ creatinine for the conjugates in serum and urine samples. The method enabled us to acquire unique concentration profiles of 12 endogenous estrogens and their intact conjugates in 30 breast cancer patients before and after one month of exemestane treatment. Exemestane suppressed total serum and urinary estrogens by 11–97% (P < 0.0001) and 8.7–91% (P < 0.0001), respectively. Specifically, these data show that exemestane preferentially suppressed E1, E1-3S, E1-3G, and E2-17G more than other estrogens. Linear regression analysis of estrogen concentrations before and after treatment showed correlation coefficients of 0.8385 (n = 289, P < 0.0001) and 0.8863 (n = 360, P < 0.0001). This study provides urinary and blood estrogen concentration profiles in breast cancer patients to demonstrate the effect of exemestane on estrogen generation, supporting inhibition of aromatase activity.     

Considerations on modelling the market for softwood lumber in the United States

The analysis in this paper looks at two important elements in modelling the market for timber in the United States. First, the issue of directional causality between price and quantity and its implications in a modelling effort is investigated. Second, the extent of the geographic market for timber is discussed and a method of detecting it is suggested. The method for detecting the extent of the geographical market is tractable and can be applied in a straightforward way. Both considerations are applied to the softwood lumber market in the United States.     

Conversion of unpolarized light to polarized light with greater than 50% efficiency by photorefractive two-beam coupling

All known polarizers operate through a separation of orthogonal electric field components, one of which is subsequently discarded. As a result, 50% of the unpolarized incident light is wasted in the process of conversion to polarized light. We demonstrate a new method by which we use the optical power in the ordinarily discarded component as the pump to amplify the retained component through photorefractive two-beam coupling to achieve greater than 50% throughput.     

On a problem of Byrnes concerning polynomials with restricted coefficients, II

As in the earlier paper with this title, we consider a question of Byrnes concerning the minimal length of a polynomial with all coefficients in which has a zero of a given order at . In that paper we showed that for all and showed that the extremal polynomials for were those conjectured by Byrnes, but for that rather than . A polynomial with was exhibited for , but it was not shown there that this extremal was unique. Here we show that the extremal is unique. In the previous paper, we showed that is one of the 7 values or . Here we prove that without determining all extremal polynomials. We also make some progress toward determining . As in the previous paper, we use a combination of number theoretic ideas and combinatorial computation. The main point is that if is a primitive th root of unity where is a prime, then the condition that all coefficients of be in , together with the requirement that be divisible by puts severe restrictions on the possible values for the cyclotomic integer .

     

Observation of an excited charm baryon Omega c* decaying to Omega c0gamma

We report the first observation of an excited singly charmed baryon Omega c* (css) in the radiative decay Omega c0gamma, where the Omega c0 baryon is reconstructed in the decays to the final states Omega(-)pi+, Omega(-)pi+pi0, Omega(-)pi+pi(-)pi+, and Xi(-)K(-)pi+pi+. This analysis is performed using a data set of 230.7 fb(-1) collected by the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center. The mass difference between the Omega c* and the Omega c0 baryons is measured to be 70.8+/-1.0(stat)+/-1.1(syst) MeV/c2. We also measure the ratio of inclusive production cross sections of Omega c* and Omega c0 in e+e(-) annihilation.