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Metal–insulator–metal (MIM) resonant absorbers comprise a conducting ground plane, a thin dielectric, and thin separated metal top-surface structures. The dielectric SiO2 strongly absorbs near 9 µm wavelength and has correspondingly strong long-wave-infrared (LWIR) dispersion for the refractive index. This dispersion results in multiple absorption resonances spanning the LWIR, which can enhance broad-band sensitivity for LWIR bolometers. Similar considerations apply to silicon nitride Si3N4. TiO2 and AlN have comparatively low dispersion and give simple single LWIR resonances. These dispersion-dependent features for infrared MIM devices are demonstrated by experiment, electrodynamic simulation, and an analytic model based on standing waves.
Outstanding problems concerning mass-loss from evolved stars include initial wind acceleration and what determines the clumping scale. Reconstructing physical conditions from maser data has been highly uncertain due to the exponential amplification. ALMA and e-MERLIN now provide image cubes for five H2O maser transitions around VY CMa, at spatial resolutions comparable to the size of individual clouds or better, covering excitation states from 204 to 2360 K. We use the model of Gray et al. 2016, to constrain variations of number density and temperature on scales of a few au, an order of magnitude finer than is possible with thermal lines, comparable to individual cloud sizes or locally almost homogeneous regions. We compare results with the models of Decin et al. 2006 and Matsuura et al. 2014 for the circumstellar envelope of VY CMa; in later work this will be extended to other maser sources.
Theoretical simulations have shown that magnetic fields play an important role in massive star formation: they can suppress fragmentation in the star forming cloud, enhance accretion via disc and regulate outflows and jets. However, models require specific magnetic configurations and need more observational constraints to properly test the impact of magnetic fields. We investigate the magnetic field structure of the massive protostar IRAS18089-1732, analysing 6.7 GHz CH3OH maser MERLIN observations. IRAS18089-1732 is a well studied high mass protostar, showing a hot core chemistry, an accretion disc and a bipolar outflow. An ordered magnetic field oriented around its disc has been detected from previous observations of polarised dust. This gives us the chance to investigate how the magnetic field at the small scale probed by masers relates to the large scale field probed by the dust.
Low resting respiratory sinus arrhythmia (RSA), and to a lesser extent excessive RSA reactivity to emotion evocation, are observed in many psychiatric disorders characterized by emotion dysregulation, including syndromes spanning the internalizing and externalizing spectra, and other conditions such as nonsuicidal self-injury. Nevertheless, some inconsistencies exist. For example, null outcomes in studies of RSA–emotion dysregulation relations are sometimes observed among younger participants. Such findings may derive from use of age inappropriate frequency bands in calculating RSA. We combine data from five published samples (N = 559) spanning ages 4 to 17 years, and reanalyze RSA data using age-appropriate respiratory frequencies. Misspecifying respiratory frequencies results in overestimates of resting RSA and underestimates of RSA reactivity, particularly among young children. Underestimates of developmental shifts in RSA and RSA reactivity from preschool to adolescence were also observed. Although correlational analyses revealed weak negative associations between resting RSA and aggression, those with clinical levels of externalizing exhibited lower resting RSA than their peers. No associations between RSA reactivity and externalizing were observed. Results confirm that age-corrected frequency bands should be used when estimating RSA, and that literature-wide overestimates of resting RSA, underestimates of RSA reactivity, and underestimates of developmental shifts in RSA and RSA reactivity may exist.
The surface waters of the Southern Ocean play a key role in the global climate and carbon cycles by promoting growth of some of the world’s largest phytoplankton blooms. Several studies have emphasized the importance of glacial and sediment inputs of Fe that fuel the primary production of the Fe-limited Southern Ocean. Although the fertile surface waters along the shelf of the western Antarctic Peninsula (WAP) are influenced by large inputs of freshwater, this freshwater may take multiple pathways (e.g. calving, streams, groundwater discharge) with different degrees of water-rock interactions leading to variable Fe flux to coastal waters. During the summers of 2012–13 and 2013–14, seawater samples were collected along the WAP, near Anvers Island, to observe water column dynamics in nearshore and offshore waters. Tracers (223,224Ra, 222Rn, 18O, 2H) were used to evaluate the source and transport of water and nutrients in coastal fjords and across the shelf. Coastal waters are compared across two field seasons, with increased freshwater observed during 2014. Horizontal mixing rates of water masses along the WAP ranged from 110–3600 m2 s-1. These mixing rates suggest a rapid transport mechanism for moving meltwater offshore.
A snow crystal has been successfully collected on to a scanning electron microscope (SEM) stub in central Greenland. It was preserved at liquid-nitrogen temperature for 5 months, prior to examination in the SEM. This is believed to be the first time a snow crystal has been observed directly in the SEM and offers some new experimental methods for understanding crystals and their chemistry.
We present the results of two imaging surveys for companions to low-luminosity dwarfs, one with Keck to a limiting magnitude of K = 20, and the other with HST to a limiting magnitude of I = 23. No companions were found at separations of 0″.5 to 20″.0, but seven companions were found within 0″.5. Based on sub-stellar evolutionary models, we estimate the companion detection efficiency as a function of mass ratio. This modeling, coupled with the data, place strong upper limits on the mass ratios of unobserved companions. We conclude that no companions exist in the optimal sensitivity regions of both surveys for q > 0.85 (HST), and q > 0.4 (Keck).
Many archaeological sites along coastlines and rivers contain large quantities of marine and riverine bivalve shell. Often shell is the only datable organic material available to determine radiocarbon age estimates of features and to build regional chronologies. Shell is difficult to date accurately because of reservoir effects, and archaeologists have avoided it despite its abundance. If reservoir effects are understood, shell can provide accurate radiocarbon age estimates. This report provides an example using regression relations computed from radiocarbon assays of paired shelll charcoal samples from archaeological sites along the middle and lower Snake River, Northwestern North America.
An experimental X-ray powder diffraction pattern was produced and analyzed for imipenem monohydrate, an antimicrobial pharmaceutical agent. Although there are no experimental powder patterns in the ICDD PDF-4/Organics Database, there is one powder pattern calculated with single-crystal X-ray diffraction data from the Cambridge Structural Database. Here, we report the refined experimental powder diffraction data for imipenem monohydrate. These data for imipenem monohydrate are consistent with an orthorhombic crystal system having reduced unit-cell parameters of a = 8.2534(3) Å, b = 11.1293(4) Å, and c = 15.4609(6) Å. The resulting unit-cell volume, 1420.15(15) Å3, indicates four formula units per unit cell. Observed peaks are consistent with the P212121 space group.
We have the honour of submitting on behalf of the Executive Committee a report of the operations carried out by the Silchester Excavation Fund in 1900.
The work was begun on the 4th May under the direction of Mr. Frederick Davis, whose death in July last has deprived the Committee of valuable services freely given and intelligently performed. The further conduct of the work was undertaken by Mr. Mill Stephenson and Mr. Hope, and the closing operations, which were prolonged until 4th December, were also directed by Mr. Stephenson.
The viability of Gas Immersion Laser Doping (GILD) for VLSI processing of ultra shallow junctions is assessed using chemical, electrical and structural characterization of boron doped diodes. Diodes with good ideality factors (1.1) overarange of junction depths (50nm Xj 200 nm) have been fabricated by GILD. This process uses a pulsed XeCI excimer laserincident on a silicon surface saturated with B2H6.
Dopant profiles as a function of laser energy and number of pulses aredetermined using Secondary Ion Mass Spectrometry(SIMS). For low energy or a large number of pulses, comparison with computer modelling suggests the junction is determined by melt depth. For higher laser energy and few pulses, liquid phase diffusion limits the depth of dopant incorporation.
Leakage current measurements as a function of diode perimeter to area (P/A) ratio and Deep Level Transient Spectroscopy (DLTS) suggest that leakage occurs along the diode perimeter, and is dueto point defects generated from thermal stresses during melt regrowth. Diodes show good I-V characteristics after GILD alone, yet subsequent rapid thermal annealingisfound to further reduce leakage currents, probably due to relief of thermal stresses. Sheet carrier densities from Halleffect measurements show that 5 - 10% of the boron is activated, with doping levels exceeding 1020 cm−3 in some samples. Transmission Electron Microscopy (TEM) demonstrates that reasonable crystalline quality is maintained for moderate GILD conditions with a defect density at the surface of approximately 108 cm−2 .For higher laser energy with boron incorporation exceeding solid solubility, TEM shows stacking faults along <110>directions. Electron diffraction on highly doped samples shows extra spots indicating a high degree of strain in the doped layer.
The mortality patterns obtained with S. dublin injected intraperitoneally in both control and immunized mice could be described fairly well by curves of a simple Poisson type, based upon the assumption that the receipt of one or more organisms of a type capable of growing in the host resulted in death, and that both vaccination and passive protection simply reduced the proportion of this type.
We consider the diffusion of a magnetic field in a stationary medium where the electrical conductivity along field lines (σ∥) differs from that across them (σ⊥), and by showing that in the limit σ⊥/σ∥ → 0 the fields remain force-free, some unusual features of force-free evolution are clarified.
Equations describing the resistive evolution of a cylindrically symmetric magnetic field through force-free states enable us to study its response to externally applied electric fields. The process is relaxational, and, under certain conditions, the final state is a reversed field configuration. We show, moreover, that the non-standard nature of the equations leads to a non-trivial (adiabatic) evolution in the case of vanishing resistivity.