152 research outputs found
Cataclysmic Variables in the First Year of the Zwicky Transient Facility
Using selection criteria based on amplitude, time, and color, we have identified 329 objects as known or candidate cataclysmic variables (CVs) during the first year of testing and operation of the Zwicky Transient Facility. Of these, 90 are previously confirmed CVs, 218 are strong candidates based on the shape and color of their light curves obtained during 3–562 days of observation, and the remaining 21 are possible CVs but with too few data points to be listed as good candidates. Almost half of the strong candidates are within 10 deg of the galactic plane, in contrast to most other large surveys that have avoided crowded fields. The available Gaia parallaxes are consistent with sampling the low mass transfer CVs, as predicted by population models. Our follow-up spectra have confirmed Balmer/helium emission lines in 27 objects, with four showing high-excitation He ii emission, including candidates for an AM CVn, a polar, and an intermediate polar. Our results demonstrate that a complete survey of the Galactic plane is needed to accomplish an accurate determination of the number of CVs existing in the Milky Way
First-year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results: Hubble Diagram and Cosmological Parameters
We present measurements of the Hubble diagram for 103 Type Ia supernovae
(SNe) with redshifts 0.04 < z < 0.42, discovered during the first season (Fall
2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data
fill in the redshift "desert" between low- and high-redshift SN Ia surveys. We
combine the SDSS-II measurements with new distance estimates for published SN
data from the ESSENCE survey, the Supernova Legacy Survey, the Hubble Space
Telescope, and a compilation of nearby SN Ia measurements. Combining the SN
Hubble diagram with measurements of Baryon Acoustic Oscillations from the SDSS
Luminous Red Galaxy sample and with CMB temperature anisotropy measurements
from WMAP, we estimate the cosmological parameters w and Omega_M, assuming a
spatially flat cosmological model (FwCDM) with constant dark energy equation of
state parameter, w. For the FwCDM model and the combined sample of 288 SNe Ia,
we find w = -0.76 +- 0.07(stat) +- 0.11(syst), Omega_M = 0.306 +- 0.019(stat)
+- 0.023(syst) using MLCS2k2 and w = -0.96 +- 0.06(stat) +- 0.12(syst), Omega_M
= 0.265 +- 0.016(stat) +- 0.025(syst) using the SALT-II fitter. We trace the
discrepancy between these results to a difference in the rest-frame UV model
combined with a different luminosity correction from color variations; these
differences mostly affect the distance estimates for the SNLS and HST
supernovae. We present detailed discussions of systematic errors for both
light-curve methods and find that they both show data-model discrepancies in
rest-frame -band. For the SALT-II approach, we also see strong evidence for
redshift-dependence of the color-luminosity parameter (beta). Restricting the
analysis to the 136 SNe Ia in the Nearby+SDSS-II samples, we find much better
agreement between the two analysis methods but with larger uncertainties.Comment: Accepted for publication by ApJ
The effectiveness and cost-effectiveness of the ‘Walk with Me’ peer-led walking intervention to increase physical activity in inactive older adults:Study protocol for a randomised controlled trial
Background: The proportion of the population aged 65 years or older is increasing. Typically, physical activity and health decline with age, which is why action to promote active ageing is a major public health priority, particularly due to health inequalities in older adults. The aim of this study is to assess the effectiveness and cost-effectiveness of the Walk with Me peer-led walking intervention for older adults. Methods: This study is a two-arm, assessor-blind, randomised controlled trial. The intervention is a 12-week peer-led walking intervention based on social cognitive theory. Participants in the control group will receive information on active ageing and healthy nutrition. The study will target 348 community-dwelling older adults, aged 60 years or over living in areas of socio-economic disadvantage communities. Trained peer mentors will deliver the intervention. The primary outcome will be a mean between-group change in moderate-to-vigorous physical activity at 12 months from baseline, measured using an Actigraph accelerometer. Secondary outcomes will include quality of life, mental wellbeing, blood pressure, BMI and waist circumference. An embedded process evaluation will involve focus groups and participant diaries. Discussion: Evidence-based, cost-effective interventions to promote physical activity in older adults living in socio-economically disadvantaged communities are needed to address health inequalities
Block of C/EBPα function by phosphorylation in acute myeloid leukemia with FLT3 activating mutations
Mutations constitutively activating FLT3 kinase are detected in ∼30% of acute myelogenous leukemia (AML) patients and affect downstream pathways such as extracellular signal–regulated kinase (ERK)1/2. We found that activation of FLT3 in human AML inhibits CCAAT/enhancer binding protein α (C/EBPα) function by ERK1/2-mediated phosphorylation, which may explain the differentiation block of leukemic blasts. In MV4;11 cells, pharmacological inhibition of either FLT3 or MEK1 leads to granulocytic differentiation. Differentiation of MV4;11 cells was also observed when C/EBPα mutated at serine 21 to alanine (S21A) was stably expressed. In contrast, there was no effect when serine 21 was mutated to aspartate (S21D), which mimics phosphorylation of C/EBPα. Thus, our results suggest that therapies targeting the MEK/ERK cascade or development of protein therapies based on transduction of constitutively active C/EBPα may prove effective in treatment of FLT3 mutant leukemias resistant to the FLT3 inhibitor therapies
Discovery of an intermediate-luminosity red transient in M51 and its likely dust-obscured, infrared-variable progenitor
We present the discovery of an optical transient (OT) in Messier 51,
designated M51 OT2019-1 (also ZTF19aadyppr, AT 2019abn, ATLAS19bzl), by the
Zwicky Transient Facility (ZTF). The OT rose over 15 days to an observed
luminosity of (), in the
luminosity gap between novae and typical supernovae (SNe). Spectra during the
outburst show a red continuum, Balmer emission with a velocity width of
km s, Ca II and [Ca II] emission, and absorption features
characteristic of an F-type supergiant. The spectra and multiband light curves
are similar to the so-called "SN impostors" and intermediate-luminosity red
transients (ILRTs). We directly identify the likely progenitor in archival
Spitzer Space Telescope imaging with a m luminosity of
and a color redder than 0.74 mag, similar
to those of the prototype ILRTs SN 2008S and NGC 300 OT2008-1. Intensive
monitoring of M51 with Spitzer further reveals evidence for variability of the
progenitor candidate at [4.5] in the years before the OT. The progenitor is not
detected in pre-outburst Hubble Space Telescope optical and near-IR images. The
optical colors during outburst combined with spectroscopic temperature
constraints imply a higher reddening of mag and higher
intrinsic luminosity of
() near peak than seen in previous ILRT
candidates. Moreover, the extinction estimate is higher on the rise than on the
plateau, suggestive of an extended phase of circumstellar dust destruction.
These results, enabled by the early discovery of M51 OT2019-1 and extensive
pre-outburst archival coverage, offer new clues about the debated origins of
ILRTs and may challenge the hypothesis that they arise from the
electron-capture induced collapse of extreme asymptotic giant branch stars.Comment: 21 pages, 5 figures, published in ApJ
PTF10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99
The Palomar Transient Factory (PTF) is systematically charting the optical
transient and variable sky. A primary science driver of PTF is building a
complete inventory of transients in the local Universe (distance less than 200
Mpc). Here, we report the discovery of PTF10fqs, a transient in the luminosity
"gap" between novae and supernovae. Located on a spiral arm of Messier 99, PTF
10fqs has a peak luminosity of Mr = -12.3, red color (g-r = 1.0) and is slowly
evolving (decayed by 1 mag in 68 days). It has a spectrum dominated by
intermediate-width H (930 km/s) and narrow calcium emission lines. The
explosion signature (the light curve and spectra) is overall similar to thatof
M85OT2006-1, SN2008S, and NGC300OT. The origin of these events is shrouded in
mystery and controversy (and in some cases, in dust). PTF10fqs shows some
evidence of a broad feature (around 8600A) that may suggest very large
velocities (10,000 km/s) in this explosion. Ongoing surveys can be expected to
find a few such events per year. Sensitive spectroscopy, infrared monitoring
and statistics (e.g. disk versus bulge) will eventually make it possible for
astronomers to unravel the nature of these mysterious explosions.Comment: 12 pages, 12 figures, Replaced with published versio
Evaluation of chronic lymphocytic leukemia by oligonucleotide-based microarray analysis uncovers novel aberrations not detected by FISH or cytogenetic analysis
<p>Abstract</p> <p>Background</p> <p>Cytogenetic evaluation is a key component of the diagnosis and prognosis of chronic lymphocytic leukemia (CLL). We performed oligonucleotide-based comparative genomic hybridization microarray analysis on 34 samples with CLL and known abnormal karyotypes previously determined by cytogenetics and/or fluorescence <it>in situ </it>hybridization (FISH).</p> <p>Results</p> <p>Using a custom designed microarray that targets >1800 genes involved in hematologic disease and other malignancies, we identified additional cryptic aberrations and novel findings in 59% of cases. These included gains and losses of genes associated with cell cycle regulation, apoptosis and susceptibility loci on 3p21.31, 5q35.2q35.3, 10q23.31q23.33, 11q22.3, and 22q11.23.</p> <p>Conclusions</p> <p>Our results show that microarray analysis will detect known aberrations, including microscopic and cryptic alterations. In addition, novel genomic changes will be uncovered that may become important prognostic predictors or treatment targets for CLL in the future.</p
Long-rising Type II Supernovae in the Zwicky Transient Facility Census of the Local Universe
SN 1987A was an unusual hydrogen-rich core-collapse supernova originating
from a blue supergiant star. Similar blue supergiant explosions remain a small
family of events, and are broadly characterized by their long rises to peak.
The Zwicky Transient Facility (ZTF) Census of the Local Universe (CLU)
experiment aims to construct a spectroscopically complete sample of transients
occurring in galaxies from the CLU galaxy catalog. We identify 13 long-rising
(>40 days) Type II supernovae from the volume-limited CLU experiment during a
3.5 year period from June 2018 to December 2021, approximately doubling the
previously known number of these events. We present photometric and
spectroscopic data of these 13 events, finding peak r-band absolute magnitudes
ranging from -15.6 to -17.5 mag and the tentative detection of Ba II lines in 9
events. Using our CLU sample of events, we derive a long-rising Type II
supernova rate of Mpc yr,
1.4% of the total core-collapse supernova rate. This is the first
volumetric rate of these events estimated from a large, systematic,
volume-limited experiment.Comment: 32 pages, 17 figures, 5 tables. Submitted to Ap
Primary and secondary defences of squid to cruising and ambush fish predators : variable tactics and their survival value
Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Animal Behaviour 81 (2011): 585-594, doi:10.1016/j.anbehav.2010.12.002.Longfin squid (Loligo pealeii) were exposed to two predators, bluefish (Pomatomus
saltatrix) and summer flounder (Paralichthys dentatus), representing cruising and ambush
foraging tactics, respectively. During 35 trials, 86 predator–prey interactions were evaluated
between bluefish and squid, and in 29 trials, 92 interactions were assessed between flounder and
squid. With bluefish, squid predominantly used stay tactics (68.6%, 59/86) as initial responses.
The most common stay response was to drop to the bottom, while showing a disruptive body
pattern, and remain motionless. In 37.0% (34/92) of interactions with flounder, squid did not
detect predators camouflaging on the bottom and showed no reaction prior to being attacked.
Squid that did react, used flee tactics more often as initial responses (43.5%, 40/92), including
flight with or without inking. When all defence behaviours were considered concurrently, flight
was identified as the strongest predictor of squid survival during interactions with each predator.
Squid that used flight at any time during an attack sequence had high probabilities of survival
with bluefish (65%, 20/31) and flounder (51%, 18/35). The most important deimatic/protean
behaviour used by squid was inking. Inking caused bluefish to startle (deimatic) and abandon
attacks (probability of survival = 61%, 11/18) and caused flounder to misdirect (protean) attacks
towards ink plumes rather than towards squid (probability of survival = 56%, 14/25). These are
the first published laboratory experiments to evaluate the survival value of antipredator
behaviours in a cephalopod. Results demonstrate that squid vary their defence tactics in response
to different predators and that the effectiveness of antipredator behaviours is contingent upon the
behavioural characteristics of the predator encountered.This study was funded by the Woods Hole Oceanographic Institution Sea Grant
Program, the Massachusetts Marine Fisheries Institute, the University of Massachusetts and the
Five College Coastal and Marine Sciences Program. R. T. Hanlon acknowledges partial support
from ONR grant N000140610202 and the Sholley Foundation
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