The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a novel transit radio telescope operating across the 400-800-MHz band. CHIME is comprised of four 20-m x 100-m semi-cylindrical ...paraboloid reflectors, each of which has 256 dual-polarization feeds suspended along its axis, giving it a >200 square degree field-of-view. This, combined with wide bandwidth, high sensitivity, and a powerful correlator makes CHIME an excellent instrument for the detection of Fast Radio Bursts (FRBs). The CHIME Fast Radio Burst Project (CHIME/FRB) will search beam-formed, high time-and frequency-resolution data in real time for FRBs in the CHIME field-of-view. Here we describe the CHIME/FRB backend, including the real-time FRB search and detection software pipeline as well as the planned offline analyses. We estimate a CHIME/FRB detection rate of 2-42 FRBs/sky/day normalizing to the rate estimated at 1.4-GHz by Vander Wiel et al. (2016). Likely science outcomes of CHIME/FRB are also discussed. CHIME/FRB is currently operational in a commissioning phase, with science operations expected to commence in the latter half of 2018.
We present an overview of the 'ICE' hardware and software framework that implements large arrays of interconnected FPGA-based data acquisition, signal processing and networking nodes economically. ...The system was conceived for application to radio, millimeter and sub-millimeter telescope readout systems that have requirements beyond typical off-the-shelf processing systems, such as careful control of interference signals produced by the digital electronics, and clocking of all elements in the system from a single precise observatory-derived oscillator. A new generation of telescopes operating at these frequency bands and designed with a vastly increased emphasis on digital signal processing to support their detector multiplexing technology or high-bandwidth correlators---data rates exceeding a terabyte per second---are becoming common. The ICE system is built around a custom FPGA motherboard that makes use of an Xilinx Kintex-7 FPGA and ARM-based co-processor. The system is specialized for specific applications through software, firmware, and custom mezzanine daughter boards that interface to the FPGA through the industry-standard FMC specifications. For high density applications, the motherboards are packaged in 16-slot crates with ICE backplanes that implement a low-cost passive full-mesh network between the motherboards in a crate, allow high bandwidth interconnection between crates, and enable data offload to a computer cluster. A Python-based control software library automatically detects and operates the hardware in the array. Examples of specific telescope applications of the ICE framework are presented, namely the frequency-multiplexed bolometer readout systems used for the SPT and Simons Array and the digitizer, F-engine, and networking engine for the CHIME and HIRAX radio interferometers.
The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a new 400-800MHz radio interferometer under development for deployment in South Africa. HIRAX will comprise 1024 six meter ...parabolic dishes on a compact grid and will map most of the southern sky over the course of four years. HIRAX has two primary science goals: to constrain Dark Energy and measure structure at high redshift, and to study radio transients and pulsars. HIRAX will observe unresolved sources of neutral hydrogen via their redshifted 21-cm emission line (`hydrogen intensity mapping'). The resulting maps of large-scale structure at redshifts 0.8-2.5 will be used to measure Baryon Acoustic Oscillations (BAO). HIRAX will improve upon current BAO measurements from galaxy surveys by observing a larger cosmological volume (larger in both survey area and redshift range) and by measuring BAO at higher redshift when the expansion of the universe transitioned to Dark Energy domination. HIRAX will complement CHIME, a hydrogen intensity mapping experiment in the Northern Hemisphere, by completing the sky coverage in the same redshift range. HIRAX's location in the Southern Hemisphere also allows a variety of cross-correlation measurements with large-scale structure surveys at many wavelengths. Daily maps of a few thousand square degrees of the Southern Hemisphere, encompassing much of the Milky Way galaxy, will also open new opportunities for discovering and monitoring radio transients. The HIRAX correlator will have the ability to rapidly and eXperimentciently detect transient events. This new data will shed light on the poorly understood nature of fast radio bursts (FRBs), enable pulsar monitoring to enhance long-wavelength gravitational wave searches, and provide a rich data set for new radio transient phenomena searches. This paper discusses the HIRAX instrument, science goals, and current status.
The large-scale distribution of neutral hydrogen in the Universe will be luminous through its 21 cm emission. Here, for the first time, we use the auto-power spectrum of 21 cm intensity fluctuations ...to constrain neutral hydrogen fluctuations at z~0.8. Our data were acquired with the Green Bank Telescope and span the redshift range 0.6 < z < 1 over two fields totalling ~41 deg. sq. and 190 h of radio integration time. The dominant synchrotron foregrounds exceed the signal by ~10^3, but have fewer degrees of freedom and can be removed efficiently. Even in the presence of residual foregrounds, the auto-power can still be interpreted as an upper bound on the 21 cm signal. Our previous measurements of the cross-correlation of 21 cm intensity and the WiggleZ galaxy survey provide a lower bound. Through a Bayesian treatment of signal and foregrounds, we can combine both fields in auto- and cross-power into a measurement of Omega_HI b_HI = 0.62^{+0.23}_{-0.15} * 10^{-3} at 68% confidence with 9% systematic calibration uncertainty, where Omega_HI is the neutral hydrogen (HI) fraction and b_HI is the HI bias parameter. We describe observational challenges with the present data set and plans to overcome them.
In this letter, 21 cm intensity maps acquired at the Green Bank Telescope are cross-correlated with large-scale structure traced by galaxies in the WiggleZ Dark Energy Survey. The data span the ...redshift range 0.6 < z < 1 over two fields totaling ~41 deg. sq. and 190 hours of radio integration time. The cross-correlation constrains Omega_HI b_HI r = 0.43 \pm 0.07 (stat.) \pm 0.04(sys.) x 10^-3, where Omega_HI is the neutral hydrogen HI fraction, r is the galaxy-hydrogen correlation coefficient, and b_HI is the HI bias parameter. This is the most precise constraint on neutral hydrogen density fluctuations in a challenging redshift range. Our measurement improves the previous 21 cm cross-correlation at z ~ 0.8 both in its precision and in the range of scales probed.
Human differentiation on the basis of gender is a fundamental phenomenon that affects virtually every aspect of people's daily lives. This article presents the social cognitive theory of gender role ...development and functioning. It specifies how gender conceptions are constructed from the complex mix of experiences and how they operate in concert with motivational and self-regulatory mechanisms to guide gender-linked conduct throughout the life course. The theory integrates psychological and sociostructural determinants within a unified conceptual structure. In this theoretical perspective, gender conceptions and roles are the product of a broad network of social influences operating interdependently in a variety of societal subsystems. Human evolution provides bodily structures and biological potentialities that permit a range of possibilities rather than dictate a fixed type of gender differentiation. People contribute to their self-development and bring about social changes that define and structure gender relationships through their agentic actions within the interrelated systems of influence.
Tuberous sclerosis (TSC) is a autosomal dominant genetic disorder caused by mutations in either TSC1 or TSC2, and characterized by benign hamartoma growth. We developed a murine model of Tsc1 disease ...by gene targeting. Tsc1 null embryos die at mid-gestation from a failure of liver development. Tsc1 heterozygotes develop kidney cystadenomas and liver hemangiomas at high frequency, but the incidence of kidney tumors is somewhat lower than in Tsc2 heterozygote mice. Liver hemangiomas were more common, more severe and caused higher mortality in female than in male Tsc1 heterozygotes. Tsc1 null embryo fibroblast lines have persistent phosphorylation of the p70S6K (S6K) and its substrate S6, that is sensitive to treatment with rapamycin, indicating constitutive activation of the mTOR-S6K pathway due to loss of the Tsc1 protein, hamartin. Hyperphosphorylation of S6 is also seen in kidney tumors in the heterozygote mice, suggesting that inhibition of this pathway may have benefit in control of TSC hamartomas.
A comprehensive picture of the interface between aqueous solutions and the (110) surface of rutile (α-TiO2) is being developed by combining molecular-scale and macroscopic approaches, including ...experimental measurements, quantum calculations, molecular simulations, and Gouy−Chapman−Stern models. In situ X-ray reflectivity and X-ray standing-wave measurements are used to define the atomic arrangement of adsorbed ions, the coordination of interfacial water molecules, and substrate surface termination and structure. Ab initio calculations and molecular dynamics simulations, validated through direct comparison with the X-ray results, are used to predict ion distributions not measured experimentally. Potentiometric titration and ion adsorption results for rutile powders having predominant (110) surface expression provide macroscopic constraints of electrical double layer (EDL) properties (e.g., proton release) which are evaluated by comparison with a three-layer EDL model including surface oxygen proton affinities calculated using ab initio bond lengths and partial charges. These results allow a direct correlation of the three-dimensional, crystallographically controlled arrangements of various species (H2O, Na+, Rb+, Ca2+, Sr2+, Zn2+, Y3+, Nd3+) with macroscopic observables (H+ release, metal uptake, zeta potential) and thermodynamic/electrostatic constraints. All cations are found to be adsorbed as “inner sphere” species bonded directly to surface oxygen atoms, while the specific binding geometries and reaction stoichiometries are dependent on ionic radius. Ternary surface complexes of sorbed cations with electrolyte anions are not observed. Finally, surface oxygen proton affinities computed using the MUSIC model are improved by incorporation of ab initio bond lengths and hydrogen bonding information derived from MD simulations. This multitechnique and multiscale approach demonstrates the compatibility of bond-valence models of surface oxygen proton affinities and Stern-based models of the EDL structure, with the actual molecular interfacial distributions observed experimentally, revealing new insight into EDL properties including specific binding sites and hydration states of sorbed ions, interfacial solvent properties (structure, diffusivity, dielectric constant), surface protonation and hydrolysis, and the effect of solution ionic strength.
The detailed solvation structure at the (110) surface of rutile (α-TiO2) in contact with bulk liquid water has been obtained primarily from experimentally verified classical molecular dynamics (CMD) ...simulations of the ab initio-optimized surface in contact with SPC/E water. The results are used to explicitly quantify H-bonding interactions, which are then used within the refined MUSIC model framework to predict surface oxygen protonation constants. Quantum mechanical molecular dynamics (QMD) simulations in the presence of freely dissociable water molecules produced H-bond distributions around deprotonated surface oxygens very similar to those obtained by CMD with nondissociable SPC/E water, thereby confirming that the less computationally intensive CMD simulations provide accurate H-bond information. Utilizing this H-bond information within the refined MUSIC model, along with manually adjusted Ti−O surface bond lengths that are nonetheless within 0.05 Å of those obtained from static density functional theory (DFT) calculations and measured in X-ray reflectivity experiments (as well as bulk crystal values), give surface protonation constants that result in a calculated zero net proton charge pH value (pHznpc) at 25 °C that agrees quantitatively with the experimentally determined value (5.4 ± 0.2) for a specific rutile powder dominated by the (110) crystal face. Moreover, the predicted pHznpc values agree to within 0.1 pH unit with those measured at all temperatures between 10 and 250 °C. A slightly smaller manual adjustment of the DFT-derived Ti−O surface bond lengths was sufficient to bring the predicted pHznpcvalue of the rutile (110) surface at 25 °C into quantitative agreement with the experimental value (4.8 ± 0.3) obtained from a polished and annealed rutile (110) single crystal surface in contact with dilute sodium nitrate solutions using second harmonic generation (SHG) intensity measurements as a function of ionic strength. Additionally, the H-bond interactions between protolyzable surface oxygen groups and water were found to be stronger than those between bulk water molecules at all temperatures investigated in our CMD simulations (25, 150 and 250 °C). Comparison with the protonation scheme previously determined for the (110) surface of isostructural cassiterite (α-SnO2) reveals that the greater extent of H-bonding on the latter surface, and in particular between water and the terminal hydroxyl group (Sn−OH) results in the predicted protonation constant for that group being lower than for the bridged oxygen (Sn−O−Sn), while the reverse is true for the rutile (110) surface. These results demonstrate the importance of H-bond structure in dictating surface protonation behavior, and that explicit use of this solvation structure within the refined MUSIC model framework results in predicted surface protonation constants that are also consistent with a variety of other experimental and computational data.
Diabetes mellitus (DM) is a group of chronic metabolic disorders characterized by persistent hyperglycemia. In our study, we analyzed the level and location of RAP1 changes in the development of ...β-cell dysfunction induced by glucotoxicity. We employed three pancreatic β-cell lines, namely INS-1, 1.2B4, and NIT-1, as well as a streptozotocin-induced diabetes rat model. We demonstrate that after high glucose treatment, RAP1 is increased, probably through induction by AKT, allowing RAP1 to shuttle from the nucleus to the cytoplasm and activate NF-κB signaling. Furthermore, non-enzymatic post-translational modifications of RAP1, such as advanced glycation end products and carbonylation may affect the function of RAP1, such as activation of the NF-κB signaling. Taken together, we showed that RAP1 is a new player in the mechanism of glucotoxicity in pancreatic β-cells.
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•RAP1 as a new player in the mechanism of glucotoxicity in pancreatic β-cells.•High glucose induces nucleo-cytoplasmic translocation of RAP1 in pancreatic β-cells.•Non-enzymatic post-translational RAP1 modifications can alter the function of RAP1.
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