First Asteroseismic Analysis of the Globular Cluster M80: Multiple Populations and Stellar Mass Loss

Asteroseismology provides a new avenue for accurately measuring the masses of evolved globular cluster (GC) stars through the detection of their solar-like oscillations. We present the first detections of solar-like oscillations in 47 red giant branch (RGB) and early asymptotic giant branch (EAGB) stars in the metal-poor GC M80; only the second ever with measured seismic masses. We investigate two major areas of stellar evolution and GC science; the multiple populations and stellar mass-loss. We detected a distinct bimodality in the EAGB mass distribution. We showed that this is likely due to sub-population membership. If confirmed, it would be the first direct measurement of a mass difference between sub-populations. A mass difference was not detected between the sub-populations in our RGB sample. We instead measured an average RGB mass of 0.782\pm0.009~\msun, which we interpret as the average between the sub-populations. Differing mass-loss rates on the RGB has been proposed as the second parameter that could explain the horizontal branch (HB) morphology variations between GCs. We calculated an integrated RGB mass-loss separately for each sub-population: 0.12\pm0.02~\msun (SP1) and 0.25\pm0.02~\msun (SP2). Thus, SP2 stars have greatly enhanced mass-loss on the RGB. Mass-loss is thought to scale with metallicity, which we confirm by comparing our results to a higher metallicity GC, M4. We also find that M80 stars have insignificant mass-loss on the HB. This is different to M4, suggesting that there is a metallicity and temperature dependence in the HB mass-loss. Finally, our study shows the robustness of the $\Delta\nu$-independent mass scaling relation in the low-metallicity (and low-surface gravity) regime.Comment: 20 pages, 11 figure

Could a Protist help us understand cancer?

Cancer is a deadly disease which affects millions of people globally. Cancer ultimately arises from dysregulation of growth pathways, leading to loss of cell cycle control and tumor formation. Cancer cells maintain constant cell division, evade immune detection, ignore signals for apoptosis, and may acquire the ability to degrade the extracellular matrix and metastasize. Tetrahymena thermophila are free-living (non-parasitic) ciliated unicellular eukaryotes belonging to Kingdom Protista. They are often used as a model system because they are relatively inexpensive and easy to culture and maintain. In addition, it is relatively simple to grow and harvest large numbers of cells for biochemical applications such as protein, DNA, or RNA purification. Because of their adaptability as a model system, we asked whether whether Tetrahymena possessed two common pathways often dysregulated in cancer; the Wnt signaling pathway and the Ras signaling pathway. In order to test our hypothesis, we used the Tetrahymena genome database to search for homologs of Wnt, Ras, and Raf. In addition, we used a Wnt agonist and an antagonist of Ras/Raf inhibition to determine whether the mitotic rate would be affected. While the Wnt agonist had no significant affect on mitosis, the Ras/Raf inhibitor significantly decreased mitotic rate in this organism. We also found homologs of Ras and Raf in the Tetrahymena genome database. Further studies are needed in order to obtain an accurate dose-response curve with the Ras/Raf inhibitor, BAY-293

Characterization of a Laminin-like Protein in the Kinetodesmal Fibers of Tetrahymena thermophila

Tetrahymena thermophila are free-living ciliated organisms belonging to Kingdom Protista. These organisms possess large numbers of cilia that are used for feeding as well as locomotion. The cilia are attached to microtubule organizing centers (MTOC) called basal bodies, which are rich in centrin, a calcium binding protein present in MTOCs. Because of the mechanical stress that ciliary beating puts on the plasma membrane, these cells have kinetodesmal fibers, composed of bundled coiled-coil proteins which grow from the proximal end of the basal bodies and stabilize the plasma membrane. Laminin is a cross-linking protein found in the extracellular matrix of animals. Using an antibody against laminin-b1, we found that the antibody localized to kinetodesmal fibers which overlapped the basal bodies stained by the anti-centrin antibody. To determine whether these proteins were in the same complex, we did co-immunoprecipitation using both our anti-centrin and anti-laminin antibodies. Both antibodies precipitated centrin (a doublet at 20 kD) as well as a number of presumed laminin-like proteins between 37 and 50 kD. We also found a number of laminin homologues in the Tetrahymena Genome Database. Further studies will be needed to determine which of these putative proteins is present in the kinetodesmal fiber

Using Watershed Boundaries to Map Adverse Health Outcomes: Examples From Nebraska, USA

In 2009, a paper was published suggesting that watersheds provide a geospatial platform for establishing linkages between aquatic contaminants, the health of the environment, and human health. This article is a follow-up to that original article. From an environmental perspective, watersheds segregate landscapes into geospatial units that may be relevant to human health outcomes. From an epidemiologic perspective, the watershed concept places anthropogenic health data into a geospatial framework that has environmental relevance. Research discussed in this article includes information gathered from the literature, as well as recent data collected and analyzed by this research group. It is our contention that the use of watersheds to stratify geospatial information may be both environmentally and epidemiologically valuable

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM