ALBERT

Description: We have assembled a data set of 165 low redshift, z 〈 0.06, publicly available Type Ia supernovae (SNe Ia). We produce maximum light magnitude ( M B and M V ) distributions of SNe Ia to explore the diversity of parameter space that they can fill. Before correction for host galaxy extinction we find that the mean M B and M V of SNe Ia are –18.58 ± 0.07 and –18.72 ± 0.05 mag, respectively. Host galaxy extinction is corrected using a new method based on the SN spectrum. After correction, the mean values of M B and M V of SNe Ia are –19.10 ± 0.06 and –19.10 ± 0.05 mag, respectively. After correction for host galaxy extinction, ‘normal’ SNe Ia ( m 15 ( B ) 〈 1.6 mag) fill a larger parameter space in the width–luminosity relation than previously suggested, and there is evidence for luminous SNe Ia with large m 15 ( B ). We find a bimodal distribution in m 15 ( B ), with a pronounced lack of transitional events at m 15 ( B ) = 1.6 mag. We confirm that faster, low-luminosity SNe tend to come from passive galaxies. Dividing the sample by host galaxy type, SNe Ia from star-forming (S-F) galaxies have a mean M B = –19.20 ± 0.05 mag, while SNe Ia from passive galaxies have a mean M B = –18.57 ± 0.24 mag. Even excluding fast declining SNe, ‘normal’ ( M B 〈 –18 mag) SNe Ia from S-F and passive galaxies are distinct. In the V band, there is a difference of 0.4 ± 0.13 mag between the median ( M V ) values of the ‘normal’ SN Ia population from passive and S-F galaxies. This is consistent with (~15 ± 10) per cent of ‘normal’ SNe Ia from S-F galaxies coming from an old stellar population.

Description: A new method to study the intrinsic colour and luminosity of Type Ia supernovae (SNe Ia) is presented. A metric space built using principal component analysis on a spectral series for SNe Ia between –12.5 and +17.5 d from the B maximum is used as a set of predictors. This metric space is built to be insensitive to reddening. Hence, it does not predict the part of the colour excess due to dust extinction. At the same time, the rich variability of SN Ia spectra is a good predictor of a large fraction of the intrinsic colour variability. Such a metric space is a good predictor of the epoch when the maximum in the B  –  V colour curve is reached. Multivariate partial least-squares regression predicts the intrinsic B -band light curve and the intrinsic B  –  V colour curve up to a month after the maximum. This allows us to study the relation between the light curves of SNe Ia and their spectra. The total-to-selective extinction ratio R V in the host galaxy of SNe Ia is found, on average, to be consistent with typical Milky Way values. This analysis shows the importance of collecting spectra to study SNe Ia, even with a large sample publicly available. Future automated surveys, such as the Large Synoptic Survey Telescope, will provide a large number of light curves. The analysis shows that observing accompanying spectra for a significant number of SNe will be important even for normal SNe Ia.

Description: The optical and optical/near-infrared pseudo-bolometric light curves of 85 stripped-envelope supernovae (SNe) are constructed using a consistent method and a standard cosmology. The light curves are analysed to derive temporal characteristics and peak luminosity L p , enabling the construction of a luminosity function. Subsequently, the mass of 56 Ni synthesized in the explosion, along with the ratio of ejecta mass to ejecta kinetic energy, are found. Analysis shows that host-galaxy extinction is an important factor in accurately determining luminosity values as it is significantly greater than Galactic extinction in most cases. It is found that broad-lined SNe Ic (SNe Ic-BL) and gamma-ray burst SNe are the most luminous subtypes with a combined median L p , in erg s –1 , of log( L p ) = 43.00 compared to 42.51 for SNe Ic, 42.50 for SNe Ib, and 42.36 for SNe IIb. It is also found that SNe Ic-BL synthesize approximately twice the amount of 56 Ni compared with SNe Ic, Ib, and IIb, with median M Ni = 0.34, 0.16, 0.14, and 0.11 M , respectively. SNe Ic-BL, and to a lesser extent SNe Ic, typically rise from L p /2 to L p more quickly than SNe Ib/IIb; consequently, their light curves are not as broad.

Description: Several two-stage multiple testing procedures have been proposed to detect gene-environment interaction in genome-wide association studies. In this article, we elucidate general conditions that are required for validity and power of these procedures, and we propose extensions of two-stage procedures using the case-only estimator of gene-treatment interaction in randomized clinical trials. We develop a unified estimating equation approach to proving asymptotic independence between a filtering statistic and an interaction test statistic in a range of situations, including marginal association and interaction in a generalized linear model with a canonical link. We assess the performance of various two-stage procedures in simulations and in genetic studies from Women’s Health Initiative clinical trials.

Description: In addition to the genetic constitution inherited by an organism, the developmental trajectory and resulting mature phenotype are also determined by mechanisms acting during critical windows in early life that influence and establish stable patterns of gene expression. This is the crux of the developmental origins of health and disease hypothesis that suggests undernutrition during gestation and infancy predisposes to ill health in later life. The hypothesis that periconceptional maternal micronutrient supplementation might affect fetal genome-wide methylation within gene promoters was explored in cord blood samples from offspring of Gambian women enrolled into a unique randomized, double blind controlled trial. Significant changes in the epigenome in cord blood DNA samples were further explored in a subset of offspring at 9 months. Gender-specific changes related to periconceptional nutritional supplementation were identified in cord blood DNA samples, some of which showed persistent changes in infant blood DNA samples. Significant effects of periconceptional micronutrient supplementation were also observed in postnatal samples which were not evident in cord blood. In this Gambian population, the increased death rate of individuals born in nutritionally poor seasons has been related to infection and it is of interest that we identified differential methylation at genes associated with defence against infection and immune response. Although the sample size was relatively small, these pilot data suggest that periconceptional nutrition in humans is an important determinant of newborn whole genome methylation patterns but may also influence postnatal developmental patterns of gene promoter methylation linking early with disease risk.

Description: While there is considerable interest in transforming even-aged stands into species-diverse, irregular structures, the rarity of stands close to the end of the transformation process has resulted in a lack of knowledge on optimum target structures that are considered sustainable. This study examined this problem in a mixed-species selection stand that has undergone transformation for over 60 years. Complete inventories of a one-hectare permanent sample plot were carried out in 2015 and previously in 2009, 2003 and 1997. The diameter distribution remained relatively static with the q factor remaining at 1.4 since the 2009 inventory. An improvement in the number of regenerating seedlings and saplings available for recruitment from previous inventories suggests that the current structure is relatively stable although shade-tolerating conifers are gradually dominating the stand. Not all the sustainability criteria were met; however, the stand could be described as having reached a balanced condition. It is recommended that the current stocking density and basal area (~350 stems ha –1 and 26–27 m 2 ha –1 , respectively) should be maintained and that future harvesting interventions should aim to reduce the number of large diameter stems (〉55 cm DBH), which represent 14 per cent of the stocking but 48 per cent of the stand basal area.

Description: The Clayton–Oakes bivariate failure time model is extended to dimensions $m 〉 2$ in a manner that allows unspecified marginal survivor functions for all dimensions less than $m$ . Special cases that allow unspecified marginal survivor functions of dimension $q$ or less with $q 〈 m$ , while making some provisions for dependencies of dimension greater than $q$ , are also described.

Description: SUMMARY We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into five main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans—particularly well preserved in the arid environment of the Gobi region—allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is ∼1 mm yr –1 along the WIB and EIB segments and ∼0.5 mm yr –1 along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault. Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, reflecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at M w 7.78–7.95. Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of ∼2500–5200 yr for past earthquakes along the different segments of the western Bogd Fault. This suggests that the three western segments of the Bogd Fault and the Gurvan Bulag thrust fault (a reverse fault bounding the southern side of the Ih Bogd range that ruptured during the 1957 earthquake) have similar average recurrence times, and therefore may have ruptured together in previous earthquakes as they did in 1957. These results suggest that the western part of the Bogd Fault system, including the Gurvan Bulag thrust fault, usually behaves in a ‘characteristic earthquake’ mode.

Description: We studied the interplay between 39 breast cancer (BC) risk SNPs and established BC risk (body mass index, height, age at menarche, parity, age at menopause, smoking, alcohol and family history of BC) and prognostic factors (TNM stage, tumor grade, tumor size, age at diagnosis, estrogen receptor status and progesterone receptor status) as joint determinants of BC risk. We used a nested case–control design within the National Cancer Institute's Breast and Prostate Cancer Cohort Consortium (BPC3), with 16 285 BC cases and 19 376 controls. We performed stratified analyses for both the risk and prognostic factors, testing for heterogeneity for the risk factors, and case–case comparisons for differential associations of polymorphisms by subgroups of the prognostic factors. We analyzed multiplicative interactions between the SNPs and the risk factors. Finally, we also performed a meta-analysis of the interaction ORs from BPC3 and the Breast Cancer Association Consortium. After correction for multiple testing, no significant interaction between the SNPs and the established risk factors in the BPC3 study was found. The meta-analysis showed a suggestive interaction between smoking status and SLC4A7 -rs4973768 ( P interaction = 8.84 x 10 –4 ) which, although not significant after considering multiple comparison, has a plausible biological explanation. In conclusion, in this study of up to almost 79 000 women we can conclusively exclude any novel major interactions between genome-wide association studies hits and the epidemiologic risk factors taken into consideration, but we propose a suggestive interaction between smoking status and SLC4A7 -rs4973768 that if further replicated could help our understanding in the etiology of BC.

Description: Predicting the large-scale consequences of drought in contrasting environments requires that we understand how drought effects differ among species originating from those environments. A previous meta-analysis of published experiments suggested that the effects of drought on both stomatal and non-stomatal limitations to photosynthesis may vary consistently among species from different hydroclimates. Here, we explicitly tested this hypothesis with two short-term water stress experiments on congeneric mesic and xeric species. One experiment was run in Australia using Eucalyptus species and the second was run in Spain using Quercus species as well as two more mesic species. In each experiment, plants were grown under moist conditions in a glasshouse, then deprived of water, and gas exchange was monitored. The stomatal response was analysed with a recently developed stomatal model, whose single parameter g 1 represents the slope of the relationship between stomatal conductance and photosynthesis. The non-stomatal response was partitioned into effects on mesophyll conductance ( g m ), the maximum Rubisco activity ( V cmax ) and the maximum electron transport rate ( J max ). We found consistency among the drought responses of g 1 , g m , V cmax and J max , suggesting that drought imposes limitations on Rubisco activity and RuBP regeneration capacity concurrently with declines in stomatal and mesophyll conductance. Within each experiment, the more xeric species showed relatively high g 1 under moist conditions, low drought sensitivity of g 1 , g m , V cmax and J max , and more negative values of the critical pre-dawn water potential at which V cmax declines most steeply, compared with the more mesic species. These results indicate adaptive interspecific differences in drought responses that allow xeric tree species to continue transpiration and photosynthesis for longer during periods without rain.