Low-Mass Eclipsing Binaries in the Initial Kepler Data Release

We identify 231 objects in the newly released Cycle 0 dataset from the Kepler Mission as double-eclipse, detached eclipsing binary systems with Teff < 5500 K and orbital periods shorter than ~32 days. We model each light curve using the JKTEBOP code with a genetic algorithm to obtain precise values for each system. We identify 95 new systems with both components below 1.0 M_sun and eclipses of at least 0.1 magnitudes, suitable for ground-based follow-up. Of these, 14 have periods less than 1.0 day, 52 have periods between 1.0 and 10.0 days, and 29 have periods greater than 10.0 days. This new sample of main-sequence, low-mass, double-eclipse, detached eclipsing binary candidates more than doubles the number of previously known systems, and extends the sample into the completely heretofore unexplored P > 10.0 day period regime. We find preliminary evidence from these systems that the radii of low-mass stars in binary systems decrease with period. This supports the theory that binary spin-up is the primary cause of inflated radii in low-mass binary systems, although a full analysis of each system with radial-velocity and multi-color light curves is needed to fully explore this hypothesis. As well, we present 7 new transiting planet candidates that do not appear among the recently released list of 706 candidates by the Kepler team, nor in the Kepler False Positive Catalog, along with several other new and interesting systems. We also present novel techniques for the identification, period analysis, and modeling of eclipsing binaries.Comment: 22 pages in emulateapj format. 9 figures, 4 tables, 2 appendices. Accepted to AJ. Includes a significant addition of new material since last arXiv submission and an updated method for estimating masses and radi

Global fetal DNA methylation and birth outcomes in obese women

Pregnant women who are obese are more likely to have gestational diabetes, gestational hypertension, pre-eclampsia, macrosomia, operative vaginal delivery, and cesarean delivery. Obesity also has adverse implications for the neonate. Congenital anomalies are more common in children born to obese women. These include neural tube defects, gastroschisis, cardiovascular anomalies, and others. Although the connection between maternal obesity and chronic health conditions has been described, the mechanism by which this occurs is less well understood. Changes to the epigenetic structure of offspring DNA have been proposed as one such mechanism

H19/miR-675 non-coding RNA expression differentiates among cancers of the human endometrium.

H19 is a maternally expressed non-coding RNA located at chromosome 11p15.5 near the reciprocally imprinted insulin-like growth factor 2 (IGF2) gene. Though the function of H19 is unknown, it is transcribed during embryonic development after which transcription is absent in all but a few tissues including cardiac muscle, breast, ovary, uterus, and placenta. Linking H19, miR-675 and RB1 expression with serous tumors of the endometrium suggests that RB1 suppression may be a differentiating event in serous tumorigenesis

Kepler Cycle 1 Observations of Low Mass Stars: New Eclipsing Binaries, Single Star Rotation Rates, and the Nature and Frequency of Starspots

We have analyzed Kepler light curves for 849 stars with T_eff < 5200 K from our Cycle 1 Guest Observer program. We identify six new eclipsing binaries, one of which has an orbital period of 29.91 d, and two of which are probably W UMa variables. In addition, we identify a candidate "warm Jupiter" exoplanet. We further examine a subset of 670 sources for variability. Of these objects, 265 stars clearly show periodic variability that we assign to rotation of the low-mass star. At the photometric precision level provided by Kepler, 251 of our objects showed no evidence for variability. We were unable to determine periods for 154 variable objects. We find that 79% of stars with T_eff < 5200 K are variable. The rotation periods we derive for the periodic variables span the range 0.31 < P_rot < 126.5 d. A considerable number of stars with rotation periods similar to the solar value show activity levels that are 100 times higher than the Sun. This is consistent with results for solar-like field stars. As has been found in previous studies, stars with shorter rotation periods generally exhibit larger modulations. This trend flattens beyond P_rot = 25 d, demonstrating that even long period binaries may still have components with high levels of activity and investigating whether the masses and radii of the stellar components in these systems are consistent with stellar models could remain problematic. Surprisingly, our modeling of the light curves suggests that the active regions on these cool stars are either preferentially located near the rotational poles, or that there are two spot groups located at lower latitudes, but in opposing hemispheres.Comment: 48 pages, 11 figure

Trash-to-Gas: Using Waste Products to Minimize Logistical Mass During Long Duration Space Missions

Just as waste-to-energy processes utilizing municipal landftll and biomass wastes are finding increased terrestrial uses, the Trash-to-Gas (TtG) project seeks to convert waste generated during spaceflight into high value commodities. These include methane for propulsion and water for life support in addition to a variety of other gasses. TtG is part of the Logistic Reduction and Repurposing (LRR) project under the NASA Advanced Exploration Systems Program. The LRR project will enable a largely mission-independent approach to minimize logistics contributions to total mission architecture mass. LRR includes technologies that reduce the amount of consumables that need to be sent to space, repurpose items sent to space, or convert wastes to commodities. Currently, waste generated on the International Space Station is stored inside a logistic module which is de-orbited into Earth's atmosphere for destruction. The waste consists of food packaging, food, clothing and other items. This paper will discuss current results on incineration as a waste processing method. Incineration is part of a two step process to produce methane from waste: first the waste is converted to carbon oxides; second, the carbon oxides are fed to a Sabatier reactor where they are converted to methane. The quantities of carbon dioxide, carbon monoxide, methane and water were measured under the different thermal degradation conditions. The overall carbon conversion efficiency and water recovery are discussed

A Method For Eclipsing Component Identification In Large Photometric Datasets

We describe an automated method for assigning the most likely physical parameters to the components of an eclipsing binary (EB), using only its photometric light curve and combined color. In traditional methods (e.g. WD and EBOP) one attempts to optimize a multi-parameter model over many iterations, so as to minimize the chi-squared value. We suggest an alternative method, where one selects pairs of coeval stars from a set of theoretical stellar models, and compares their simulated light curves and combined colors with the observations. This approach greatly reduces the EB parameter-space over which one needs to search, and allows one to determine the components' masses, radii and absolute magnitudes, without spectroscopic data. We have implemented this method in an automated program using published theoretical isochrones and limb-darkening coefficients. Since it is easy to automate, this method lends itself to systematic analyses of datasets consisting of photometric time series of large numbers of stars, such as those produced by OGLE, MACHO, TrES, HAT, and many others surveys.Comment: 6 pages, 5 figures. To appear in the conference proceedings of "Close Binaries in the 21st Century: New Opportunities and Challenges", Syros, Greece, 27-30 June, 200

The generation of phase differences and frequency changes in a network model of inferior olive subthreshold oscillations

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedicationIt is commonly accepted that the Inferior Olive (IO) provides a timing signal to the cerebellum. Stable subthreshold oscillations in the IO can facilitate accurate timing by phase-locking spikes to the peaks of the oscillation. Several theoretical models accounting for the synchronized subthreshold oscillations have been proposed, however, two experimental observations remain an enigma. The first is the observation of frequent alterations in the frequency of the oscillations. The second is the observation of constant phase differences between simultaneously recorded neurons. In order to account for these two observations we constructed a canonical network model based on anatomical and physiological data from the IO. The constructed network is characterized by clustering of neurons with similar conductance densities, and by electrical coupling between neurons. Neurons inside a cluster are densely connected with weak strengths, while neurons belonging to different clusters are sparsely connected with stronger connections. We found that this type of network can robustly display stable subthreshold oscillations. The overall frequency of the network changes with the strength of the inter-cluster connections, and phase differences occur between neurons of different clusters. Moreover, the phase differences provide a mechanistic explanation for the experimentally observed propagating waves of activity in the IO. We conclude that the architecture of the network of electrically coupled neurons in combination with modulation of the inter-cluster coupling strengths can account for the experimentally observed frequency changes and the phase differences.Peer reviewedFinal Published versio

A Small Conductance Calcium-Activated K⁺ Channel in C. elegans, KCNL-2, Plays a Role in the Regulation of the Rate of Egg-Laying

In the nervous system of mice, small conductance calcium-activated potassium (SK) channels function to regulate neuronal excitability through the generation of a component of the medium afterhyperpolarization that follows action potentials. In humans, irregular action potential firing frequency underlies diseases such as ataxia, epilepsy, schizophrenia and Parkinson's disease. Due to the complexity of studying protein function in the mammalian nervous system, we sought to characterize an SK channel homologue, KCNL-2, in C. elegans, a genetically tractable system in which the lineage of individual neurons was mapped from their early developmental stages. Sequence analysis of the KCNL-2 protein reveals that the six transmembrane domains, the potassium-selective pore and the calmodulin binding domain are highly conserved with the mammalian homologues. We used widefield and confocal fluorescent imaging to show that a fusion construct of KCNL-2 with GFP in transgenic lines is expressed in the nervous system of C. elegans. We also show that a KCNL-2 null strain, kcnl-2(tm1885), demonstrates a mild egg-laying defective phenotype, a phenotype that is rescued in a KCNL-2-dependent manner. Conversely, we show that transgenic lines that overexpress KCNL-2 demonstrate a hyperactive egg-laying phenotype. In this study, we show that the vulva of transgenic hermaphrodites is highly innervated by neuronal processes and by the VC4 and VC5 neurons that express GFP-tagged KCNL-2. We propose that KCNL-2 functions in the nervous system of C. elegans to regulate the rate of egg-laying. © 2013 Chotoo et al