259 research outputs found
Temperature dependence of field-response mechanisms in 0.4Ba(Zr\u3csub\u3e0.2\u3c/sub\u3eTi\u3csub\u3e0.8\u3c/sub\u3e)O\u3csub\u3e3\u3c/sub\u3e-0.6(Ba\u3csub\u3e0.7\u3c/sub\u3eCa\u3csub\u3e0.3\u3c/sub\u3e)TiO\u3csub\u3e3\u3c/sub\u3e
Understanding the temperature dependence of how ferroelectric materials respond to electric fields is critical for determining how best to use these materials in applications. Here, temperature dependent in situ x-ray diffraction is used to study how field-response mechanism Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 evolves with temperature. Increasing the measurement temperature was found to slightly reduce the extent of domain reversal and the magnitude of the 111 lattice strain. Instead, these results indicate that temperature predominantly impacted the angular dependence of the 002/200 lattice strain. We attribute the observed differences in 002/200 lattice strain to the flattening of the free-energy near the tetragonal-orthorhombic phase boundary, where the flattening of the energy landscape promotes a polarization rotation response during the application of electric fields at room temperature
Cyclical DNA Methyltransferase 3a Expression Is a Seasonal and Estrus Timer in Reproductive Tissues
Acknowledgments We thank Gerald Lincoln for his critical feedback on a previous version of this manuscript. Author contributions included the following: T.J.S. conceived the project, designed the experiments, analyzed the data, and wrote the manuscript. E.W.J.L. conducted the experiments and analyzed the data. C.S.C. conducted the immunocytochemistry. M.L. conducted the HEK293 cell culture assays. E.M.C. and A.S.B. provided technical assistance. This work was supported by the University of Aberdeen College of Life Sciences and Medicine grant (to T.J.S.). E.W.J.L. was supported by a Society for Reproduction and Fertility undergraduate scholarship. Disclosure Summary: The authors have nothing to disclose.Peer reviewedPostprin
Effects of Feeding a Novel Alfalfa Leaf Pellet Product (ProLEAF MAX) and Alfalfa Stems (ProFiber Plus) on Performance in the Feedlot and Carcass Quality of Beef Steers
Alfalfa is often included in the diets of beef animals; however, the nutrient content of alfalfa is variable depending on the region in which it is grown, climate, soil, and many other factors. The leaf portion of alfalfa has a less variable nutrient composition than the stem portion of the plant. The variability that is present in the alfalfa plant can make the development of total mixed rations of consistent nutrient content difficult. As such, the purpose of this study was to determine how the inclusion of fractionated alfalfa leaves and alfalfa stems impacts performance and carcass quality of finishing beef steers. Twenty-four steers were allocated to one of three treatments: a control group fed a typical finishing diet with alfalfa as the forage (CON; n = 8), a typical diet that replaced alfalfa with fractionated alfalfa leaf pellets and alfalfa stems (ProLEAF MAXâą + ProFiber Plusâą; PLM+PFP; n = 8), or a typical diet that replaced alfalfa with alfalfa stems (PFP; n = 8) for 63 days. Steers were fed individually once daily, weighed every 14 days and ultrasound images were collected every 28 days. At the end of the feeding trial, steers were harvested at a commercial facility and carcass data was obtained. Analysis of dry matter intake demonstrated that steers receiving the PFP and CON diets consumed more feed (P \u3c 0.001) than steers consuming the PLM+PFP diet. Steers receiving the PLM+PFP diet gained less (P \u3c 0.001) weight than the steers receiving the other two dietary treatments. No differences (P \u3e 0.10) in feed efficiency or carcass characteristics were observed. Steers receiving the PFP diet had improved (P = 0.016) cost of gain (1.08 per kg) diet. Overall, our findings demonstrate that the inclusion of PFP in place of alfalfa hay in a finishing diet has the potential to improve cost of gain, without negatively affecting growth, performance, or carcass characteristics of finishing feedlot steers
What Next-Generation 21 cm Power Spectrum Measurements Can Teach Us About the Epoch of Reionization
A number of experiments are currently working towards a measurement of the 21
cm signal from the Epoch of Reionization. Whether or not these experiments
deliver a detection of cosmological emission, their limited sensitivity will
prevent them from providing detailed information about the astrophysics of
reionization. In this work, we consider what types of measurements will be
enabled by a next-generation of larger 21 cm EoR telescopes. To calculate the
type of constraints that will be possible with such arrays, we use simple
models for the instrument, foreground emission, and the reionization history.
We focus primarily on an instrument modeled after the
collecting area Hydrogen Epoch of Reionization Array (HERA) concept design, and
parameterize the uncertainties with regard to foreground emission by
considering different limits to the recently described "wedge" footprint in
k-space. Uncertainties in the reionization history are accounted for using a
series of simulations which vary the ionizing efficiency and minimum virial
temperature of the galaxies responsible for reionization, as well as the mean
free path of ionizing photons through the IGM. Given various combinations of
models, we consider the significance of the possible power spectrum detections,
the ability to trace the power spectrum evolution versus redshift, the
detectability of salient power spectrum features, and the achievable level of
quantitative constraints on astrophysical parameters. Ultimately, we find that
of collecting area is enough to ensure a very high significance
() detection of the reionization power spectrum in even the
most pessimistic scenarios. This sensitivity should allow for meaningful
constraints on the reionization history and astrophysical parameters,
especially if foreground subtraction techniques can be improved and
successfully implemented.Comment: 27 pages, 18 figures, updated SKA numbers in appendi
The Precision Array for Probing the Epoch of Reionization: 8 Station Results
We are developing the Precision Array for Probing the Epoch of Reionization
(PAPER) to detect 21cm emission from the early Universe, when the first stars
and galaxies were forming. We describe the overall experiment strategy and
architecture and summarize two PAPER deployments: a 4-antenna array in the
low-RFI environment of Western Australia and an 8-antenna array at our
prototyping site in Green Bank, WV. From these activities we report on system
performance, including primary beam model verification, dependence of system
gain on ambient temperature, measurements of receiver and overall system
temperatures, and characterization of the RFI environment at each deployment
site.
We present an all-sky map synthesized between 139 MHz and 174 MHz using data
from both arrays that reaches down to 80 mJy (4.9 K, for a beam size of 2.15e-5
steradians at 154 MHz), with a 10 mJy (620 mK) thermal noise level that
indicates what would be achievable with better foreground subtraction. We
calculate angular power spectra () in a cold patch and determine them
to be dominated by point sources, but with contributions from galactic
synchrotron emission at lower radio frequencies and angular wavemodes. Although
the cosmic variance of foregrounds dominates errors in these power spectra, we
measure a thermal noise level of 310 mK at for a 1.46-MHz band
centered at 164.5 MHz. This sensitivity level is approximately three orders of
magnitude in temperature above the level of the fluctuations in 21cm emission
associated with reionization.Comment: 13 pages, 14 figures, submitted to AJ. Revision 2 corrects a scaling
error in the x axis of Fig. 12 that lowers the calculated power spectrum
temperatur
Different realities: a comparison of augmented and virtual reality for the sensemaking process
Analysts perform sensemaking on large complex multimedia datasets in order to extract concepts, themes, and other kinds of insights from them. Immersive analytics, in particular, puts users in virtual environments that allow them to explore data in a unique way where they can interact and move through the data. Previous research using virtual reality immersive analytics tools found users wanting to refer to real-world objects or understand the physical world around them while continuing to perform their analysis. Therefore, we designed and ran a comparative study looking at the tradeoffs between virtual and augmented reality for our immersive analytics approach: Immersive Space to Think. Through two mixed-methods studies we found that virtual reality affords users a space where users can focus more on their task, but augmented reality allows them to use various real-world tools that can increase user satisfaction. In future immersive analytics tools, we recommend a blend of the twoâaugmented virtualityâwith pass-through portals which allow users to see various real-world tools, such as whiteboards or desks and keyboards, while still giving themselves a space to focus
An analogue of row removal for diagrammatic cherednik algebras
We prove an analogue of JamesâDonkin row removal theorems for diagrammatic
Cherednik algebras. This is one of the first results concerning the (graded) decomposition numbers
of these algebras over fields of arbitrary characteristic. As a special case, our results yield a new
reduction theorem for graded decomposition numbers and extension groups for cyclotomic q-Schur
algebras
Hydrogen Epoch of Reionization Array (HERA)
The Hydrogen Epoch of Reionization Array (HERA) is a staged experiment to
measure 21 cm emission from the primordial intergalactic medium (IGM)
throughout cosmic reionization (), and to explore earlier epochs of our
Cosmic Dawn (). During these epochs, early stars and black holes
heated and ionized the IGM, introducing fluctuations in 21 cm emission. HERA is
designed to characterize the evolution of the 21 cm power spectrum to constrain
the timing and morphology of reionization, the properties of the first
galaxies, the evolution of large-scale structure, and the early sources of
heating. The full HERA instrument will be a 350-element interferometer in South
Africa consisting of 14-m parabolic dishes observing from 50 to 250 MHz.
Currently, 19 dishes have been deployed on site and the next 18 are under
construction. HERA has been designated as an SKA Precursor instrument.
In this paper, we summarize HERA's scientific context and provide forecasts
for its key science results. After reviewing the current state of the art in
foreground mitigation, we use the delay-spectrum technique to motivate
high-level performance requirements for the HERA instrument. Next, we present
the HERA instrument design, along with the subsystem specifications that ensure
that HERA meets its performance requirements. Finally, we summarize the
schedule and status of the project. We conclude by suggesting that, given the
realities of foreground contamination, current-generation 21 cm instruments are
approaching their sensitivity limits. HERA is designed to bring both the
sensitivity and the precision to deliver its primary science on the basis of
proven foreground filtering techniques, while developing new subtraction
techniques to unlock new capabilities. The result will be a major step toward
realizing the widely recognized scientific potential of 21 cm cosmology.Comment: 26 pages, 24 figures, 2 table
Field Deployment of Prototype Antenna Tiles for the Mileura Widefield Array--Low Frequency Demonstrator
Experiments were performed with prototype antenna tiles for the Mileura
Widefield Array--Low Frequency Demonstrator (MWA-LFD) to better understand the
widefield, wideband properties of their design and to characterize the radio
frequency interference (RFI) between 80 and 300 MHz at the site in Western
Australia. Observations acquired during the six month deployment confirmed the
predicted sensitivity of the antennas, sky-noise dominated system temperatures,
and phase-coherent interferometric measurements. The radio spectrum is
remarkably free of strong terrestrial signals, with the exception of two narrow
frequency bands allocated to satellite downlinks and rare bursts due to
ground-based transmissions being scattered from aircraft and meteor trails.
Results indicate the potential of the MWA-LFD to make significant achievements
in its three key science objectives: epoch of reionziation science,
heliospheric science, and radio transient detection.Comment: Accepted by AJ. 17 pages with figure
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