Faunal and erosional events in the Eastern Tethyan Sea across the K/T boundary

A regional pattern of three closely spaced erosional events at and above the K/T boundary was determined from six Cretaceous/Tertiary boundary sections in the Negev of Israel. The sections were collected from locations throughout the central and northern Negev. All sections are lithologically similar. The Maastrichtian consists of a sequence of limestone beds intercalated with thin marly beds. In some sections, the last limestone bed is followed by 1 to 2 m of calcareous marls grading upwards into several meters of grey shale. In other sections the limestone bed is followed directly by grey shale with the contact containing particles of limestone and marl. A 5 to 20 cm thick dark grey organic-rich clay layer is present about 1.5 to 2.5 m above the base of the grey shale. The grey shale grades upwards into increasingly carbonate rich marls. No unconformities are apparent in field outcrops. During field collection the dark grey clay layer was believed to represent the K/T boundary clay. Microfossil analysis however identified the boundary at the base of the grey shale. The black shale represents a low productivity anoxic event similar to, but younger than, the K/T boundary clay in other K/T boundary sections. High resolution planktic foraminiferal and carbonate analysis of these sections (at 5 to 10 cm intervals) yield surprising results. The K/T boundary is marked by an erosional event which removed part or all of the uppermost Maastrichtian marls above the last limestone bed. Percent carbonate data for four Negev sections are illustrated and show the regional similarities in carbonate sedimentation. Faunal and carbonate data from the Negev sections thus show three closely spaced short erosional events at the K/T boundary and within the first 50,000 to 100,000 years of the Danian. These K/T boundary erosional events may represent global climatic or paleoceanographic events

Detecting the Baryons in Matter Power Spectra

We examine power spectra from the Abell/ACO rich cluster survey and the 2dF Galaxy Redshift Survey (2dfGRS) for observational evidence of features produced by the baryons. A non-negligible baryon fraction produces relatively sharp oscillatory features at specific wavenumbers in the matter power spectrum. However, the mere existence of baryons will also produce a global suppression of the power spectrum. We look for both of these features using the false discovery rate (FDR) statistic. We show that the window effects on the Abell/ACO power spectrum are minimal, which has allowed for the discovery of discrete oscillatory features in the power spectrum. On the other hand, there are no statistically significant oscillatory features in the 2dFGRS power spectrum, which is expected from the survey's broad window function. After accounting for window effects, we apply a scale-independent bias to the 2dFGRS power spectrum, P_{Abell}(k) = b^2P_{2dF}(k) and b = 3.2. We find that the overall shapes of the Abell/ACO and the biased 2dFGRS power spectra are entirely consistent over the range 0.02 <= k <= 0.15hMpc^-1. We examine the range of Omega_{matter} and baryon fraction for which these surveys could detect significant suppression in power. The reported baryon fractions for both the Abell/ACO and 2dFGRS surveys are high enough to cause a detectable suppression in power (after accounting for errors, windows and k-space sampling). Using the same technique, we also examine, given the best fit baryon density obtained from BBN, whether it is possible to detect additional suppression due to dark matter-baryon interaction. We find that the limit on dark matter cross section/mass derived from these surveys are the same as those ruled out in a recent study by Chen, Hannestad and Scherrer.Comment: 11 pages of text, 6 figures. Submitted to Ap

A new source detection algorithm using FDR

The False Discovery Rate (FDR) method has recently been described by Miller et al (2001), along with several examples of astrophysical applications. FDR is a new statistical procedure due to Benjamini and Hochberg (1995) for controlling the fraction of false positives when performing multiple hypothesis testing. The importance of this method to source detection algorithms is immediately clear. To explore the possibilities offered we have developed a new task for performing source detection in radio-telescope images, Sfind 2.0, which implements FDR. We compare Sfind 2.0 with two other source detection and measurement tasks, Imsad and SExtractor, and comment on several issues arising from the nature of the correlation between nearby pixels and the necessary assumption of the null hypothesis. The strong suggestion is made that implementing FDR as a threshold defining method in other existing source-detection tasks is easy and worthwhile. We show that the constraint on the fraction of false detections as specified by FDR holds true even for highly correlated and realistic images. For the detection of true sources, which are complex combinations of source-pixels, this constraint appears to be somewhat less strict. It is still reliable enough, however, for a priori estimates of the fraction of false source detections to be robust and realistic.Comment: 17 pages, 7 figures, accepted for publication by A

Convergence towards an asymptotic shape in first-passage percolation on cone-like subgraphs of the integer lattice

In first-passage percolation on the integer lattice, the Shape Theorem provides precise conditions for convergence of the set of sites reachable within a given time from the origin, once rescaled, to a compact and convex limiting shape. Here, we address convergence towards an asymptotic shape for cone-like subgraphs of the $\Z^d$ lattice, where $d\ge2$. In particular, we identify the asymptotic shapes associated to these graphs as restrictions of the asymptotic shape of the lattice. Apart from providing necessary and sufficient conditions for $L^p$- and almost sure convergence towards this shape, we investigate also stronger notions such as complete convergence and stability with respect to a dynamically evolving environment.Comment: 23 pages. Together with arXiv:1305.6260, this version replaces the old. The main results have been strengthened and an earlier error in the statement corrected. To appear in J. Theoret. Proba

On a random walk with memory and its relation to Markovian processes

We study a one-dimensional random walk with memory in which the step lengths to the left and to the right evolve at each step in order to reduce the wandering of the walker. The feedback is quite efficient and lead to a non-diffusive walk. The time evolution of the displacement is given by an equivalent Markovian dynamical process. The probability density for the position of the walker is the same at any time as for a random walk with shrinking steps, although the two-time correlation functions are quite different.Comment: 10 pages, 4 figure

From brain to earth and climate systems: Small-world interaction networks or not?

We consider recent reports on small-world topologies of interaction networks derived from the dynamics of spatially extended systems that are investigated in diverse scientific fields such as neurosciences, geophysics, or meteorology. With numerical simulations that mimic typical experimental situations we have identified an important constraint when characterizing such networks: indications of a small-world topology can be expected solely due to the spatial sampling of the system along with commonly used time series analysis based approaches to network characterization

Palm pairs and the general mass-transport principle

We consider a lcsc group G acting properly on a Borel space S and measurably on an underlying sigma-finite measure space. Our first main result is a transport formula connecting the Palm pairs of jointly stationary random measures on S. A key (and new) technical result is a measurable disintegration of the Haar measure on G along the orbits. The second main result is an intrinsic characterization of the Palm pairs of a G-invariant random measure. We then proceed with deriving a general version of the mass-transport principle for possibly non-transitive and non-unimodular group operations first in a deterministic and then in its full probabilistic form.Comment: 26 page

Associating GWAS Information with the Notch Signaling Pathway Using Transcription Profiling

Genome-wide association studies (GWAS) have identified SNPs associated with breast cancer. However, they offer limited insights about the biological mechanisms by which SNPs confer risk. We investigated the association of GWAS information with a major oncogenic pathway in breast cancer, the Notch signaling pathway. We first identified 385 SNPs and 150 genes associated with risk for breast cancer by mining data from 41 GWAS. We then investigated their expression, along with 32 genes involved in the Notch signaling pathway using two publicly available gene expression data sets from the Caucasian (42 cases and 143 controls) and Asian (43 cases and 43 controls) populations. Pathway prediction and network modeling confirmed that Notch receptors and genes involved in the Notch signaling pathway interact with genes containing SNPs associated with risk for breast cancer. Additionally, we identified other SNP-associated biological pathways relevant to breast cancer, including the P53, apoptosis and MAP kinase pathways

Controlling the False Discovery Rate in Astrophysical Data Analysis

The False Discovery Rate (FDR) is a new statistical procedure to control the number of mistakes made when performing multiple hypothesis tests, i.e. when comparing many data against a given model hypothesis. The key advantage of FDR is that it allows one to a priori control the average fraction of false rejections made (when comparing to the null hypothesis) over the total number of rejections performed. We compare FDR to the standard procedure of rejecting all tests that do not match the null hypothesis above some arbitrarily chosen confidence limit, e.g. 2 sigma, or at the 95% confidence level. When using FDR, we find a similar rate of correct detections, but with significantly fewer false detections. Moreover, the FDR procedure is quick and easy to compute and can be trivially adapted to work with correlated data. The purpose of this paper is to introduce the FDR procedure to the astrophysics community. We illustrate the power of FDR through several astronomical examples, including the detection of features against a smooth one-dimensional function, e.g. seeing the ``baryon wiggles'' in a power spectrum of matter fluctuations, and source pixel detection in imaging data. In this era of large datasets and high precision measurements, FDR provides the means to adaptively control a scientifically meaningful quantity -- the number of false discoveries made when conducting multiple hypothesis tests.Comment: 15 pages, 9 figures. Submitted to A

Hospital admission for hyperemesis gravidarum: a nationwide study of occurrence, reoccurrence and risk factors among 8.2 million pregnancies

STUDY QUESTION: What are the maternal risk factors for hyperemesis gravidarum (HG) hospital admission, readmission and reoccurrence in a following pregnancy? SUMMARY ANSWER: Young age, less socioeconomic deprivation, nulliparity, Asian or Black ethnicity, female fetus, multiple pregnancy, history of HG in a previous pregnancy, thyroid and parathyroid dysfunction, hypercholesterolemia and Type 1 diabetes are all risk factors for HG. WHAT IS KNOWN ALREADY: Women with Black or Asian ethnicity, of young age, carrying multiple babies or singleton females, with Type 1 diabetes or with a history of HG were previously reported to be at higher risk of developing HG; however, most evidence is from small studies. Little is known about associations with other comorbidities and there is controversy over other risk factors such as parity. Estimates of HG prevalence vary and there is a little understanding of the risks of HG readmission in a current pregnancy and reoccurrence rates in subsequent pregnancies, all of which are needed for planning measures to reduce onset or worsening of the condition. STUDY DESIGN, SIZE, DURATION: We performed a population-based cohort study of pregnancies ending in live births and stillbirths using prospectively recorded secondary care records (Hospital Episode Statistics) from England. We analysed those computerized and anonymized clinical records from over 5.3 million women who had one or more pregnancies between 1997 and 2012. PARTICIPANTS/MATERIALS, SETTING, METHODS: We obtained 8 215 538 pregnancies from 5 329 101 women of reproductive age, with a total of 186 800 HG admissions occurring during 121 885 pregnancies. Multivariate logistic regression with generalized estimating equations was employed to estimate odds ratios (aOR) to assess sociodemographic, pregnancy and comorbidity risk factors for HG onset, HG readmission within a pregnancy and reoccurrence in a subsequent pregnancy. MAIN RESULTS AND THE ROLE OF CHANCE: Being younger, from a less socioeconomically deprived status, of Asian or Black ethnicity, carrying a female fetus or having a multiple pregnancy all significantly increased HG and readmission risk but only ethnicity increased reoccurrence. Comorbidities most strongly associated with HG were parathyroid dysfunction (aOR = 3.83, 95% confidence interval 2.28–6.44), hypercholesterolemia (aOR = 2.54, 1.88–3.44), Type 1 diabetes (aOR = 1.95, 1.82–2.09), and thyroid dysfunction (aOR = 1.85, 1.74–1.96). History of HG was the strongest independent risk factor (aOR = 4.74, 4.46–5.05). Women with higher parity had a lower risk of HG compared with nulliparous women (aOR = 0.90, 0.89–0.91), which was not explained by women with HG curtailing further pregnancies. LIMITATIONS, REASONS FOR CAUTION: Although this represents the largest population-based study worldwide on the topic, the results could have been biased by residual and unmeasured confounding considering that some potential important risk factors such as smoking, BMI or prenatal care could not be measured with these data. Underestimation of non-routinely screened comorbidities such as hypercholesterolemia or thyroid dysfunction could also be a cause of selection bias. WIDER IMPLICATIONS OF THE FINDINGS: The estimated prevalence of 1.5% from our study was similar to the average prevalence reported in the literature and the representativeness of our data has been validated by comparison to national statistics. Also the prevalence of comorbidities was mostly similar to other studies estimating these in the UK and other developed countries. Women with Black or Asian ethnicity, of young age, carrying multiple babies or singleton females, with Type 1 diabetes or with history of HG were confirmed to be at higher risk of HG with an unprecedented higher statistical power. We showed for the first time that socioeconomic status interacts with maternal age, that hypercholesterolemia is a potential risk factor for HG and that carrying multiple females increases risk of hyperemesis compared with multiple males. We also provided robust evidence for the association of parity with HG. Earlier recognition and management of symptoms via gynaecology day-case units or general practitioner services can inform prevention and control of consequent hospital admissions. STUDY FUNDING/COMPETING INTEREST(S): The work was founded by The Rosetrees Trust and the Stoneygate Trust. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. C.N.-P. reports personal fees from Sanofi Aventis, Warner Chilcott, Leo Pharma, UCB and Falk, outside the submitted work and she is one of the co-developers of the RCOG Green Top Guideline on HG; all other authors did not report any potential conflicts of interest