B-->pi and B-->K transitions in standard and quenched chiral perturbation theory

We study the effects of chiral logs on the heavy-->light pseudoscalar meson transition form factors by using standard and quenched chiral perturbation theory combined with the static heavy quark limit. The resulting expressions are used to indicate the size of uncertainties due to the use of the quenched approximation in the current lattice studies. They may also be used to assess the size of systematic uncertainties induced by missing chiral log terms in extrapolating toward the physical pion mass. We also provide the coefficient multiplying the quenched chiral log, which may be useful if the quenched lattice studies are performed with very light mesons.Comment: 33 pages, 8 PostScript figures, version to appear in PR

Lattice Calculation of Heavy-Light Decay Constants with Two Flavors of Dynamical Quarks

We present results for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios in the presence of two flavors of light sea quarks ($N_f=2$). We use Wilson light valence quarks and Wilson and static heavy valence quarks; the sea quarks are simulated with staggered fermions. Additional quenched simulations with nonperturbatively improved clover fermions allow us to improve our control of the continuum extrapolation. For our central values the masses of the sea quarks are not extrapolated to the physical $u$, $d$ masses; that is, the central values are "partially quenched." A calculation using "fat-link clover" valence fermions is also discussed but is not included in our final results. We find, for example, $f_B = 190 (7) (^{+24}_{-17}) (^{+11}_{-2}) (^{+8}_{-0})$ MeV, $f_{B_s}/f_B = 1.16 (1) (2) (2) (^{+4}_{-0})$, $f_{D_s} = 241 (5) (^{+27}_{-26}) (^{+9}_{-4}) (^{+5}_{-0})$ MeV, and $f_{B}/f_{D_s} = 0.79 (2) (^{+5}_{-4}) (3) (^{+5}_{-0})$, where in each case the first error is statistical and the remaining three are systematic: the error within the partially quenched $N_f=2$ approximation, the error due to the missing strange sea quark and to partial quenching, and an estimate of the effects of chiral logarithms at small quark mass. The last error, though quite significant in decay constant ratios, appears to be smaller than has been recently suggested by Kronfeld and Ryan, and Yamada. We emphasize, however, that as in other lattice computations to date, the lattice $u,d$ quark masses are not very light and chiral log effects may not be fully under control.Comment: Revised version includes an attempt to estimate the effects of chiral logarithms at small quark mass; central values are unchanged but one more systematic error has been added. Sections III E and V D are completely new; some changes for clarity have also been made elsewhere. 82 pages; 32 figure

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

An observational study to evaluate micronutrient status during enteral feeding

Background: There are few data on the optimal micronutrient composition of paediatric enteral feeds. The recent European Directive on Foods for Special Medical Purposes (1999/21/EC) did not distinguish between the composition of adult and paediatric feeds. Aims: To evaluate, in an open, observational study, the long term nutritional biochemistry of 12 children aged 1–6 years and/or 8–20 kg. Methods: The children were receiving at least 50% of their estimated average requirement (EAR) for energy from paediatric enteral formulae: 1.0 kcal/ml (Nutrison Paediatric Standard) or 1.5 kcal/ml (Nutrison Paediatric Energy Plus). Venous blood samples for trace elements, vitamins, and minerals were taken at study entry and six months later. Parents kept three day food and feed records every month. Results: Despite a median energy intake of only 75% EAR (range 52–158%), 67% (n = 8) achieved their reference nutrient intake (RNI) for all micronutrients. No significant micronutrient deficiencies were seen on blood analysis after six months. Eighty three per cent (n = 10) had vitamin B12 and 92% (n = 11) had copper intake &gt;150% RNI. Fifty eight per cent (n = 7) had high plasma B12 (&gt;733 µmol/l) and 75% (n = 9) had high serum copper (&gt;22 µmol/l) concentrations. Conclusions: Children without excess losses maintain adequate micronutrient status on long term enteral feeding. Subjects had high blood concentrations of vitamin B12 and copper, and had high dietary intakes of these micronutrients. We suggest that the maximum nutrient guidelines for paediatric enteral feeds should be more clearly defined. <br/

Enantioselective separation of enantiomeric amides on three amylose-based chiral stationary phases: Effects of backbone and carbamate side chain chiralities Authors

A series of enantiomeric amides have been chromatographed on three amylose-based chiral stationary phases (CSPs): amylose tris(3,5-dimethylphenylcarbamate) (AD-CSP), amylose tris (S-phenylethylcarbamate) (AS-CSP), and amylose tris(R-phenylethyl-carbamate) (AR-CSP). The relative retentions and enantioselectives of the solutes on the three CSPs were compared and basic structure-retention relationships developed to describe the chromatographic results. The data indicate that for these solutes the observed elution order was a function of the chirality of the amylose backbone, while the magnitude of the enantioselective separations was affected by the chirality of the carbamate side chain. Chirality 9:173–177, 1997. © 1997 Wiley-Liss, Inc

Effect of block architecture on the micellisation and gelation of block copolymers of ethylene oxide and 1,2-butylene oxide in aqueous solution

Block copolymers E106B16, E210B16 and E103B15E103 (E = oxyethylene, B = oxybutylene) were synthesised and characterised by gel permeation chromatography (for molar mass distribution) and 13C NMR spectroscopy (for number-average molar mass and composition). Surface tensiometry was used to determine critical micelle concentrations at several temperatures, and thereby values of the enthalpy of micellisation. In the case of the diblock copolymers the micellisation was athermal. Dynamic and static light scattering were used to characterise the micelles in solution, yielding micellar association number, hydrodynamic and thermodynamic radius, and the related thermodynamic expansion factor. The latter was used to correlate the dilute solution properties of the copolymer micelles with their critical gelation concentrations. The gels were studied by small-angle X-ray scattering (SAXS) in tandem with rheology (oscillatory shear). Values of the elastic dynamic modulus (G′) of the gels significantly exceeded 104 Pa across the range of temperatures (25-75°C) and frequency (0.1-100 rad s-1) explored, allowing the gels to be characterised as &apos;hard&apos;. SAXS, whether from unoriented or shear-oriented gels, showed them to comprise structures with body-centred cubic (bcc, space group Im3̄m) symmetry. In particular, the patterns from the sheared gels were indexed to a highly twinned structure in which a [111] direction of the bcc lattice lay along the shear direction, and flow was mainly in the {211} plane for E103B15E103 gels, but in the intersecting {110}, {211} and {321} planes for the diblock copolymer gels. For one copolymer, E106B16, micellar radii (calculated assuming sphericity) and association numbers in the gel were obtained. Compared with equilibrium (thermodynamic) values in dilute solution, the micellar radii were similar but the micellar association number in the gel was larger