The reversing association between advanced maternal age and child cognitive ability: evidence from three UK birth cohorts

Background Studies on advanced maternal age – defined here as age 35 or older – and children’s cognitive development report mixed evidence. Prior studies have not analysed how the time period considered in existing studies influences the association. Methods We analysed trends in the association between maternal age and cognitive development using data from the 1958 National Child Development Study (n=10969), the 1970 British Cohort Study (n=9362), and the 2001 Millennium Cohort Study (n=11600). The dependent variable measures cognitive ability at age 10/11. Cognitive scores were standardised to a mean of zero and a standard deviation of one. Results For the 1958-1970 cohorts, maternal ages 35-39 were associated with 0.06 (95% CI: -0.13, 0.00) and 0.12 (95% CI: -0.20, -0.03) standard deviations (SD) lower cognitive ability compared to mothers in the reference category (25-29), while for the 2001 cohort with 0.16 (95% CI: 0.09-0.23) SD higher cognitive ability. For maternal ages 40+ the pattern was qualitatively similar. These cross-cohort differences appeared to be explained by the fact that in the earlier cohorts advanced maternal age was associated with high parity, whereas in the 2001 cohort it was associated with socioeconomically advantaged family background. Conclusions The results suggest that the association between advanced maternal age and children’s cognitive development changed from negative in the 1958 and 1970 cohorts to positive in the 2001 cohort because of changing parental characteristics. The time period considered can constitute an important factor in determining the association between maternal age and cognitive ability

The Ray Bundle method for calculating weak magnification by gravitational lenses

We present here an alternative method for calculating magnifications in gravitational lensing calculations -- the Ray Bundle method. We provide a detailed comparison between the distribution of magnifications obtained compared with analytic results and conventional ray-shooting methods. The Ray Bundle method provides high accuracy in the weak lensing limit, and is computationally much faster than (non-hierarchical) ray shooting methods to a comparable accuracy. The Ray Bundle method is a powerful and efficient technique with which to study gravitational lensing within realistic cosmological models, particularly in the weak lensing limit.Comment: 9 pages Latex, 8 figures, submitted to MNRA

Flexible transition timing in discrete-time multistate life tables using Markov chains with rewards

Discrete-time multistate life tables are attractive because they are easier to understand and apply in comparison to their continuous-time counterparts. While such models are based on a discrete time grid, it is often useful to calculate derived magnitudes, like state occupation times, under assumptions that posit that transitions take place at other times, such as mid-period. Unfortunately, currently available models allow only a very limited set of choices about transition timing. We propose to utilize Markov chains with rewards as an intuitive and general way of modelling the timing of transitions. Combining existing discrete-time models with the rewards methodology results in an estimation strategy that features easy parameter estimation, flexible transition timing, and little theoretical overhead. We illustrate the usefulness of rewards- based multistate life tables with SHARE data for the estimation of working life expectancy using different retirement transition timings. We also demonstrate that, for the single-state case, the rewards-based multistate life tables match traditional life table methods exactly. We provide code to replicate all results of the paper, as well as R and Stata packages for general use of the method proposed

Efficacy of Different Leuprolide Administration Schedules in Premenopausal Breast Cancer: A Retrospective Review

Background Leuprolide is a safe and effective treatment of estrogen receptor–positive premenopausal breast cancer. Data from the SOFT/TEXT trials solidified leuprolide in combination with an aromatase inhibitor as an effective hormonal treatment for premenopausal breast cancer. However, the efficacy of monthly leuprolide depot compared to leuprolide depot every 3 months in combination with an aromatase inhibitor in this patient population is unclear. Patients and Methods In this single center retrospective study, 201 patients were enrolled between January 1, 2015, and October 1, 2016; 100 were included in the 7.5 mg leuprolide monthly injection plus aromatase inhibitor group and 101 in the 22.5 mg leuprolide injection every 3 months plus aromatase inhibitor group. The primary end point was the proportion of patients who experienced ovarian ablation, defined as an estradiol concentration less than 40 pg/mL and a follicle-stimulating hormone concentration of 23 to 116 mU/mL after 3 months of treatment. Significance threshold was P < .05 (2 sided). Secondary end points included disease-free survival and overall survival at 1-year follow-up, as well as adverse events reported during treatment. Results All patients in the monthly leuprolide arm experienced ovarian ablation compared to 100 (99%) of 101 patients in the arm treated every 3 months ( P = 1). The disease-free survival rate at 1 year was 95% in the monthly leuprolide arm and 97% in the arm treated every 3 months ( P = .75). The overall survival rate at 1 year was 100% in the monthly leuprolide arm and 99% in the arm treated every 3 months ( P = 1). The most common treatment-related adverse events between the 2 groups were musculoskeletal pain, hot flashes, fatigue, and insomnia. Conclusion Leuprolide acetate depot administered every 3 months is as efficacious and tolerable as a monthly injection in combination with an aromatase inhibitor for premenopausal patients with hormone receptor–positive breast cancer

Periodicity forcing words

The Dual Post Correspondence Problem asks, for a given word α, if there exists a non-periodic morphism g and an arbitrary morphism h such that g(α) = h(α). Thus α satisfies the Dual PCP if and only if it belongs to a non-trivial equality set. Words which do not satisfy the Dual PCP are called periodicity forcing, and are important to the study of word equations, equality sets and ambiguity of morphisms. In this paper, a 'prime' subset of periodicity forcing words is presented. It is shown that when combined with a particular type of morphism it generates exactly the full set of periodicity forcing words. Furthermore, it is shown that there exist examples of periodicity forcing words which contain any given factor/prefix/suffix. Finally, an alternative class of mechanisms for generating periodicity forcing words is developed, resulting in a class of examples which contrast those known already

The Effect of Variability on the Estimation of Quasar Black Hole Masses

We investigate the time-dependent variations of ultraviolet (UV) black hole mass estimates of quasars in the Sloan Digital Sky Survey (SDSS). From SDSS spectra of 615 high-redshift (1.69 < z < 4.75) quasars with spectra from two epochs, we estimate black hole masses, using a single-epoch technique which employs an additional, automated night-sky-line removal, and relies on UV continuum luminosity and CIV (1549A) emission line dispersion. Mass estimates show variations between epochs at about the 30% level for the sample as a whole. We determine that, for our full sample, measurement error in the line dispersion likely plays a larger role than the inherent variability, in terms of contributing to variations in mass estimates between epochs. However, we use the variations in quasars with r-band spectral signal-to-noise ratio greater than 15 to estimate that the contribution to these variations from inherent variability is roughly 20%. We conclude that these differences in black hole mass estimates between epochs indicate variability is not a large contributer to the current factor of two scatter between mass estimates derived from low- and high-ionization emission lines.Comment: 76 pages, 15 figures, 2 (long) tables; Accepted for publication in ApJ (November 10, 2007