2,877 research outputs found
Characterization of K2-167 b and CALM, a new stellar activity mitigation method
We report precise radial velocity (RV) observations of HD 212657 (= K2-167), a star shown by K2 to host a transiting sub-Neptune-sized planet in a 10 day orbit. Using Transiting Exoplanet Survey Satellite (TESS) photometry, we refined the planet parameters, especially the orbital period. We collected 74 precise RVs with the HARPS-N spectrograph between August 2015 and October 2016. Although this planet was first found to transit in 2015 and validated in 2018, excess RV scatter originally limited mass measurements. Here, we measure a mass by taking advantage of reductions in scatter from updates to the HARPS-N Data Reduction System (2.3.5) and our new activity mitigation method called CCF Activity Linear Model (CALM), which uses activity-induced line shape changes in the spectra without requiring timing information. Using the CALM framework, we performed a joint fit with RVs and transits using EXOFASTv2 and find and , which places K2-167 b at the upper edge of the radius valley. We also find hints of a secondary companion at a 22 day period, but confirmation requires additional RVs. Although characterizing lower-mass planets like K2-167 b is often impeded by stellar variability, these systems especially help probe the formation physics (i.e. photoevaporation, core-powered mass loss) of the radius valley. In the future, CALM or similar techniques could be widely applied to FGK-type stars, help characterize a population of exoplanets surrounding the radius valley, and further our understanding of their formation
Human DNA methylomes of neurodegenerative diseases show common epigenomic patterns
Different neurodegenerative disorders often show similar lesions, such as the presence of amyloid plaques, TAU-neurotangles and synuclein inclusions. The genetically inherited forms are rare, so we wondered whether shared epigenetic aberrations, such as those affecting DNA methylation, might also exist. The studied samples were gray matter samples from the prefrontal cortex of control and neurodegenerative disease-associated cases. We performed the DNA methylation analyses of Alzheimer's disease, dementia with Lewy bodies, Parkinson's disease and Alzheimer-like neurodegenerative profile associated with Down's syndrome samples. The DNA methylation landscapes obtained show that neurodegenerative diseases share similar aberrant CpG methylation shifts targeting a defined gene set. Our findings suggest that neurodegenerative disorders might have similar pathogenetic mechanisms that subsequently evolve into different clinical entities. The identified aberrant DNA methylation changes can be used as biomarkers of the disorders and as potential new targets for the development of new therapies
An extensible framework for multicore response time analysis
In this paper, we introduce a multicore response time analysis (MRTA) framework, which decouples response time analysis from a reliance on context independent WCET values. Instead, the analysis formulates response times directly from the demands placed on different hardware resources. The MRTA framework is extensible to different multicore architectures, with a variety of arbitration policies for the common interconnects, and different types and arrangements of local memory. We instantiate the framework for single level local data and instruction memories (cache or scratchpads), for a variety of memory bus arbitration policies, including: Round-Robin, FIFO, Fixed-Priority, Processor-Priority, and TDMA, and account for DRAM refreshes. The MRTA framework provides a general approach to timing verification for multicore systems that is parametric in the hardware configuration and so can be used at the architectural design stage to compare the guaranteed levels of real-time performance that can be obtained with different hardware configurations. We use the framework in this way to evaluate the performance of multicore systems with a variety of different architectural components and policies. These results are then used to compose a predictable architecture, which is compared against a reference architecture designed for good average-case behaviour. This comparison shows that the predictable architecture has substantially better guaranteed real-time performance, with the precision of the analysis verified using cycle-accurate simulation
Constraining the Movement of the Spiral Features and the Locations of Planetary Bodies within the AB Aur System
We present new analysis of multi-epoch, H-band, scattered light images of the
AB Aur system. We used a Monte Carlo, radiative transfer code to simultaneously
model the system's SED and H-band polarized intensity imagery. We find that a
disk-dominated model, as opposed to one that is envelope dominated, can
plausibly reproduce AB Aur's SED and near-IR imagery. This is consistent with
previous modeling attempts presented in the literature and supports the idea
that at least a subset of AB Aur's spirals originate within the disk. In light
of this, we also analyzed the movement of spiral structures in multi-epoch
H-band total light and polarized intensity imagery of the disk. We detect no
significant rotation or change in spatial location of the spiral structures in
these data, which span a 5.8 year baseline. If such structures are caused by
disk-planet interactions, the lack of observed rotation constrains the location
of the orbit of planetary perturbers to be >47 AU.Comment: 8 pages, 3 figures, 1 table, Accepted to Ap
Improving compliance to colorectal cancer screening using blood and stool based tests in patients refusing screening colonoscopy in Germany
Background Despite strong recommendations for colorectal cancer (CRC)
screening, participation rates are low. Understanding factors that affect
screening choices is essential to developing future screening strategies.
Therefore, this study assessed patient willingness to use non-invasive stool
or blood based screening tests after refusing colonoscopy. Methods
Participants were recruited during regular consultations. Demographic, health,
psychological and socioeconomic factors were recorded. All subjects were
advised to undergo screening by colonoscopy. Subjects who refused colonoscopy
were offered a choice of non-invasive tests. Subjects who selected stool
testing received a collection kit and instructions; subjects who selected
plasma testing had a blood draw during the office visit. Stool samples were
tested with the Hb/Hp Complex Elisa test, and blood samples were tested with
the Epi proColon® 2.0 test. Patients who were positive for either were advised
to have a diagnostic colonoscopy. Results 63 of 172 subjects were compliant to
screening colonoscopy (37%). 106 of the 109 subjects who refused colonoscopy
accepted an alternative non-invasive method (97%). 90 selected the Septin9
blood test (83%), 16 selected a stool test (15%) and 3 refused any test (3%).
Reasons for blood test preference included convenience of an office draw,
overall convenience and less time consuming procedure. Conclusions 97% of
subjects refusing colonoscopy accepted a non-invasive screening test of which
83% chose the Septin9 blood test. The observation that participation can be
increased by offering non-invasive tests, and that a blood test is the
preferred option should be validated in a prospective trial in the screening
setting
The state of the Martian climate
60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes
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