We present observations from 11 very low frequency (VLF)/low‐frequency (LF) receivers across the continental United States during the 21 August 2017 “Great American Solar Eclipse.” All receivers ...detected transmissions from VLF/LF beacons below 50 kHz, while seven also recorded LF beacons above 50 kHz, yielding dozens of individual transmitter‐receiver radio links. Our observations show two separable superimposed signatures: (1) a gradual rise and fall in signal levels visible on almost all paths as the eclipse advances and then declines, as VLF attenuation is reduced by the changing ionosphere under an eclipsed Sun, and (2) direct reflective scattering off the narrow 100‐km‐wide totality spot, observed more uniquely when the transmitter or receiver, if not both, are relatively close to the totality spot.
Plain Language Summary
A solar eclipse provides a unique opportunity to study a region of the upper atmosphere known as the ionosphere, which is essentially the transition zone between Earth's atmosphere and the space environment. While the Sun is known to have a dominant impact on the electrical properties of this region, it is difficult to quantify it precisely since these altitudes, 60–90 km, are too high to reach with balloons yet too low for satellites. On the other hand, the lower ionosphere plays a key role in communications and navigation. Very low frequency/low‐frequency radio waves at 3–300 kHz reflect from this region, thus allowing us to remotely diagnose the lower ionosphere. A solar eclipse is the only time when the Sun's influence rapidly turns off over a very small region. In this paper, we have analyzed dozens of diagnostic observations, namely, transmitter‐to‐receiver communications links, that allow to quantify how the lower ionosphere responded to this unique geophysical event. As the Sun's influence changes, so too does the characteristics of these very low frequency/low‐frequency transmitters detected many hundreds to thousands of miles away.
Key Points
Solar eclipse of August 2017 impacted radio wave propagation through lower ionosphere (60‐90 km)
Array of VLF/LF radio receivers observed changes that strongly varied as a function of path geometry
We observe reflective scattering from eclipse totality spot when transmitter and receiver are proximal to the spot
•Fragility curves are obtained for typical non-skewed highway bridges in Chile.•The seismic effect of seismic bars is assessed experimentally.•The fragility curves are validated with statistical ...damage from 2010 Chile earthquake.•The transverse seat width in bridges is critical to reduce the probability of collapse.
Recent earthquakes in Chile and worldwide have caused significant economic losses due to the damage on the road bridge network. To conduct seismic risk assessment studies and to improve resilience of bridges, seismic vulnerability studies are required. The main objective of this study is to construct fragility curves of typical non-skewed highway bridges in Chile. The fragility curves are obtained from an incremental dynamic analysis of a two-dimensional model of the bent cap of a two-span simply supported underpass. As most bridges are constructed with seismic tie-down bars, their constitutive behavior was obtained experimentally. A total of five seismic bar specimens were tested to characterize their cyclic behavior in bridges with and without transverse diaphragms. The incremental dynamic analysis was performed with the two horizontal components of seven seismic records obtained from the Mw 8.8, 2010 Chile earthquake. Additionally, a parametric study is conducted to assess the seismic behavior of bridges with different configurations of seismic bars, with lateral stoppers, and with varying length of the transverse seat width. Results from this study reveal that seismic bars have a limited contribution to the seismic performance of the studied bridge, especially when lateral stoppers are incorporated. Additionally, the transverse seat width is found to be critical to reduce the collapse probability of the superstructure. The provided fragility curves may be used for seismic risk assessment and to evaluate possible improvements in seismic bridge design codes.
Optical pacing of the embryonic heart Rollins, A. M; Jenkins, M. W; Duke, A. R ...
Nature photonics,
09/2010, Letnik:
4, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Light has been used to noninvasively alter the excitability of both neural and cardiac tissue 1-10. Recently, pulsed laser light has been shown to be capable of eliciting action potentials in ...peripheral nerves and in cultured cardiomyocytes 7-10. Here, we demonstrate for the first time optical pacing (OP) of an intact heart in vivo. Pulsed 1.875 μm infrared laser light was employed to lock the heart rate to the pulse frequency of the laser. A laser Doppler velocimetry (LDV) signal was used to verify the pacing. At low radiant exposures, embryonic quail hearts were reliably paced in vivo without detectable damage to the tissue, indicating that OP has great potential as a tool to study embryonic cardiac dynamics and development. In particular, OP can be utilized to control the heart rate, and thereby alter stresses and mechanically transduced signaling.
The Dark Energy Survey: Data Release 1 Abbott, T. M. C.; Abdalla, F. B.; Allam, S. ...
The Astrophysical journal. Supplement series,
12/2018, Letnik:
239, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We describe the first public data release of the Dark Energy Survey, DES DR1, consisting of reduced single-epoch images, co-added images, co-added source catalogs, and associated products and ...services assembled over the first 3 yr of DES science operations. DES DR1 is based on optical/near-infrared imaging from 345 distinct nights (2013 August to 2016 February) by the Dark Energy Camera mounted on the 4 m Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. We release data from the DES wide-area survey covering ∼5000 deg2 of the southern Galactic cap in five broad photometric bands, grizY. DES DR1 has a median delivered point-spread function of , r = 0.96, i = 0.88, z = 0.84, and Y = 0 90 FWHM, a photometric precision of <1% in all bands, and an astrometric precision of 151 . The median co-added catalog depth for a 1 95 diameter aperture at signal-to-noise ratio (S/N) = 10 is g = 24.33, r = 24.08, i = 23.44, z = 22.69, and Y = 21.44 . DES DR1 includes nearly 400 million distinct astronomical objects detected in ∼10,000 co-add tiles of size 0.534 deg2 produced from ∼39,000 individual exposures. Benchmark galaxy and stellar samples contain ∼310 million and ∼80 million objects, respectively, following a basic object quality selection. These data are accessible through a range of interfaces, including query web clients, image cutout servers, jupyter notebooks, and an interactive co-add image visualization tool. DES DR1 constitutes the largest photometric data set to date at the achieved depth and photometric precision.
Although most children with Hirschsprung disease ultimately do well, many experience a variety of ongoing problems after pull-through surgery. The most common include obstructive symptoms, soiling, ...enterocolitis and failure to thrive. The purpose of this guideline is to present a rational approach to the management of postoperative obstructive symptoms in children with Hirschsprung disease. The American Pediatric Surgical Association Board of Governors established a Hirschsprung Disease Interest Group. Group discussions, literature review and expert consensus were then used to summarize the current state of knowledge regarding causes, methods of diagnosis, and treatment approaches to children with obstructive symptoms following pull-through for Hirschsprung disease. Causes of obstructive symptoms post-pull-through include mechanical obstruction; persistent or acquired aganglionosis, hypoganglionosis, or transition zone pull-through; internal sphincter achalasia; disordered motility in the proximal intestine that contains ganglion cells; or functional megacolon caused by stool-holding behavior. An algorithm for the diagnosis and management of obstructive symptoms after a pull-through for Hirschsprung disease is presented. A stepwise, logical approach to the diagnosis and management of patients experiencing obstructive symptoms following pull-through for Hirschsprung disease can facilitate treatment.
Level of evidence
V.
Wildfires are increasing in size across the western US, leading to
increases in human smoke exposure and associated negative health impacts.
The impact of biomass burning (BB) smoke, including ...wildfires, on regional
air quality depends on emissions, transport, and chemistry, including
oxidation of emitted BB volatile organic compounds (BBVOCs) by the hydroxyl
radical (OH), nitrate radical (NO3), and ozone (O3). During the
daytime, when light penetrates the plumes, BBVOCs are oxidized mainly by
O3 and OH. In contrast, at night or in optically dense plumes, BBVOCs
are oxidized mainly by O3 and NO3. This work focuses on the
transition between daytime and nighttime oxidation, which has significant
implications for the formation of secondary pollutants and loss of nitrogen
oxides (NOx=NO+NO2) and has been understudied. We present
wildfire plume observations made during FIREX-AQ (Fire Influence on Regional
to Global Environments and Air Quality), a field campaign involving multiple
aircraft, ground, satellite, and mobile platforms that took place in the
United States in the summer of 2019 to study both wildfire and agricultural
burning emissions and atmospheric chemistry. We use observations from two
research aircraft, the NASA DC-8 and the NOAA Twin Otter, with a detailed
chemical box model, including updated phenolic mechanisms, to analyze smoke
sampled during midday, sunset, and nighttime. Aircraft observations suggest
a range of NO3 production rates (0.1–1.5 ppbv h−1) in plumes
transported during both midday and after dark. Modeled initial instantaneous
reactivity toward BBVOCs for NO3, OH, and O3 is 80.1 %, 87.7 %, and 99.6 %, respectively. Initial NO3 reactivity is 10–104
times greater than typical values in forested or urban environments, and
reactions with BBVOCs account for >97 % of NO3 loss in
sunlit plumes (jNO2 up to 4×10-3s-1), while
conventional photochemical NO3 loss through reaction with NO and
photolysis are minor pathways. Alkenes and furans are mostly oxidized by OH
and O3 (11 %–43 %, 54 %–88 % for alkenes; 18 %–55 %, 39 %–76 %, for furans, respectively), but phenolic oxidation is split between
NO3, O3, and OH (26 %–52 %, 22 %–43 %, 16 %–33 %,
respectively). Nitrate radical oxidation accounts for 26 %–52 % of
phenolic chemical loss in sunset plumes and in an optically thick plume.
Nitrocatechol yields varied between 33 % and 45 %, and NO3
chemistry in BB plumes emitted late in the day is responsible for 72 %–92 % (84 % in an optically thick midday plume) of nitrocatechol
formation and controls nitrophenolic formation overall. As a result,
overnight nitrophenolic formation pathways account for 56 %±2 % of
NOx loss by sunrise the following day. In all but one overnight plume
we modeled, there was remaining NOx (13 %–57 %) and BBVOCs
(8 %–72 %) at sunrise.
KEY MESSAGE : Spring growth in barley controlled by natural variation at Vrn-H1 and Vrn-H2 improved yield stability in marginal Syrian environments. The objective of the present study was to identify ...QTL influencing agronomic performance in rain-fed Mediterranean environments in a recombinant inbred line (RIL) population, ARKE derived from the Syrian barley landrace, Arta and the Australian feed cultivar, Keel. The population was field tested for agronomic performance at two locations in Syria for 4 years with two sowing dates, in autumn and winter. Genotypic variability in yield of the RIL population was mainly affected by year-to-year variation presumably caused by inter-annual differences in rainfall distribution. The spring growth habit and early flowering inherited from the Australian cultivar Keel increased plant height and biomass and improved yield stability in Syrian environments. QTL for yield and biomass coincided with the map location of flowering time genes, in particular the vernalisation genes Vrn-H1 and Vrn-H2. In marginal environments with terminal drought, the Vrn-H1 allele inherited from Keel improved final biomass and yield. Under changing climate conditions, such as shorter winters, reduced rainfall, and early summer drought, spring barley might thus outperform the traditional vernalisation-sensitive Syrian landraces. We present the ARKE population as a valuable genetic resource to further elucidate the genetics of drought adaptation of barley in the field.
Although most children with Hirschsprung disease ultimately achieve functional and comfortable stooling, some will experience a variety of problems after pull-through surgery. The most common ...problems include soiling, obstructive symptoms, enterocolitis, and failure to thrive. The purpose of this guideline is to present a rational approach to the management of postoperative soiling in children with Hirschsprung disease. The American Pediatric Surgical Association Hirschsprung Disease Interest Group engaged in a literature review and group discussions. Expert consensus was then used to summarize the current state of knowledge regarding causes, methods of diagnosis, and treatment approaches to children with soiling symptoms following pull-through for Hirschsprung disease. Causes of soiling after pull-through are broadly categorized as abnormalities in sensation, abnormalities in sphincter control, and “pseudo-incontinence.” A stepwise algorithm for the diagnosis and management of soiling after a pull-through for Hirschsprung disease is presented; it is our hope that this rational approach will facilitate treatment and optimize outcomes.
ABSTRACT
As the statistical power of galaxy weak lensing reaches per cent level precision, large, realistic, and robust simulations are required to calibrate observational systematics, especially ...given the increased importance of object blending as survey depths increase. To capture the coupled effects of blending in both shear and photometric redshift calibration, we define the effective redshift distribution for lensing, nγ(z), and describe how to estimate it using image simulations. We use an extensive suite of tailored image simulations to characterize the performance of the shear estimation pipeline applied to the Dark Energy Survey (DES) Year 3 data set. We describe the multiband, multi-epoch simulations, and demonstrate their high level of realism through comparisons to the real DES data. We isolate the effects that generate shear calibration biases by running variations on our fiducial simulation, and find that blending-related effects are the dominant contribution to the mean multiplicative bias of approximately $-2{{\ \rm per\ cent}}$. By generating simulations with input shear signals that vary with redshift, we calibrate biases in our estimation of the effective redshift distribution, and demonstrate the importance of this approach when blending is present. We provide corrected effective redshift distributions that incorporate statistical and systematic uncertainties, ready for use in DES Year 3 weak lensing analyses.
Objectives To evaluate whether in children born extremely preterm, indicators of sustained systemic inflammation in the first month of life are associated with cognitive impairment at school age. ...Study design A total of 873 of 966 eligible children previously enrolled in the multicenter Extremely Low Gestational Age Newborn Study from 2002 to 2004 were evaluated at age 10 years. We analyzed the relationship between elevated blood concentrations of inflammation-associated proteins in the first 2 weeks (“early elevations”; n = 812) and the third and fourth week (“late elevations”; n = 532) of life with neurocognition. Results Early elevations of C-reactive protein, tumor necrosis factor-α, interleukin (IL)-8, intercellular adhesion molecule (ICAM)-1, and erythropoietin were associated with IQ values >2 SD below the expected mean (ORs: 2.0-2.3) and with moderate to severe cognitive impairment on a composite measure of IQ and executive function (ORs: 2.1-3.6). Additionally, severe cognitive impairment was associated with late protein elevations of C-reactive protein (OR: 4.0; 95% CI 1.5, 10), IL-8 (OR: 5.0; 1.9, 13), ICAM-1 (OR: 6.5; 2.6, 16), vascular endothelial growth factor-receptor 2 (OR: 3.2; 1.2, 8.3), and thyroid-stimulating hormone (OR: 3.1; 1.3, 7.3). Moderate cognitive impairment was most strongly associated with elevations of IL-8, ICAM-1, and vascular endothelial growth factor-receptor 2. When 4 or more inflammatory proteins were elevated early, the risk of having an IQ <70 and having overall impaired cognitive ability was more than doubled (ORs: 2.1-2.4); the presence of 4 or more inflammatory protein elevated late was strongly linked to adverse cognitive outcomes (ORs: 2.9-4.8). Conclusions Extremely preterm children who had sustained elevations of inflammation-related proteins in the first postnatal month are more likely than extremely preterm peers without such elevations to have cognitive impairment at 10 years.
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