The WHAM Northern Sky Survey and the Nature of the Warm Ionized Medium in the Galaxy

The Wisconsin H-Alpha Mapper (WHAM) has completed a velocity-resolved map of diffuse H-alpha emission of the entire northern sky, providing the first comprehensive picture of both the distribution and kinematics of diffuse ionized gas in the Galaxy. WHAM continues to advance our understanding of the physical conditions of the warm ionized medium through observations of other optical emission lines throughout the Galactic disk and halo. We discuss some highlights from the survey, including an optical window into the inner Galaxy and the relationship between HI and HII in the diffuse ISM.Comment: 9 pages, 3 figures. To be published in "How does the Galaxy work?", eds. E.J. Alfaro, E. Perez & J. Franco, Kluwer, held 23-27 June 2003 in Granada, Spain. Higher resolution version available at http://www.astro.wisc.edu/~madsen/prof/pubs.htm

Ionization of Infalling Gas

H-alpha emission from neutral halo clouds probes the radiation and hydrodynamic conditions in the halo. Armed with such measurements, we can explore how radiation escapes from the Galactic plane and how infalling gas can survive a trip through the halo. The Wisconsin H-Alpha Mapper (WHAM) is one of the most sensitive instruments for detecting and mapping optical emission from the ISM. Here, we present recent results exploring the ionization of two infallling high-velocity complexes. First, we report on our progress mapping H-alpha emission covering the full extent of Complex A. Intensities are faint (<100 mR; EM <0.2 pc cm^-6 but correlate on the sky and in velocity with 21-cm emission. Second, we explore the ionized component of some Anti-Center Complex clouds studied by Peek et al. (2007) that show dynamic shaping from interaction with the Galactic halo.Comment: 4 pages, 2 figures; to appear in proceedings of "The Role of Disk-Halo Interaction in Galaxy Evolution: Outflow vs Infall?" held in Espinho, Portugal during 2008 Augus

Cut-offs and pile-ups in shock acceleration spectra

We have examined cutoffs and pile-ups due to various processes in the spectra of particles produced by shock acceleration, and found that, even in the absence of energy losses, the shape of the spectrum of accelerated particles at energies well below the nominal maximum energy depends strongly on the energy dependence of the diffusion coefficient. This has implications in many areas, for example, in fitting the observed cosmic ray spectrum with models based on power-law source spectra and rigidity dependent diffusive escape from the galaxy. With continuous energy losses, prominent pile-ups may arise, and these should be included when modelling synchrotron X-ray and inverse Compton gamma-ray spectra from a shock-accelerated electron population. We have developed a Monte Carlo/numerical technique to model the shape of the spectrum for the case of non-continuous energy losses such as inverse Compton scattering in the Klein-Nishina regime. We find that the shapes of the resulting cut-offs differ substantially from those arising from continuous processes, and we suggest that such differences could be observable through their effect on the spectrum of radiation emitted by a population of recently accelerated electrons as, for example, may exist in young supernova remnants.Comment: 23 pages, 8 figures, submitted to Astroparticle Physic

HI Clouds Beyond the Galactic Disk

Recent observations in the 21cm line with the Green Bank Telescope have changed our view of the neutral interstellar medium (ISM) in several ways. The new data show that in the inner parts of the Milky Way the disk-halo interface is composed of many discrete HI clouds. The clouds lie in a layer more than one kpc thick and follow Galactic rotation. Their origin and evolution is unknown. In the outer Galaxy, the new data show that the high-velocity cloud Complex H is likely a satellite on a retrograde orbit interacting with some extended component of the Milky Way's ISM. These observations place new constraints on models of the ISM and are directly related to the work of Don Cox and Ron Reynolds.Comment: 8 pages includes 2 figures. To appear in "How Does the Galaxy Work?", eds. E.J. Alfaro, E. Perez, & J. Franco, Kluwer, Proceedings of a Conference held 23-27 June 2003 in Granada, Spai

Is the Sun Embedded in a Typical Interstellar Cloud?

The physical properties and kinematics of the partially ionized interstellar material near the Sun are typical of warm diffuse clouds in the solar vicinity. The interstellar magnetic field at the heliosphere and the kinematics of nearby clouds are naturally explained in terms of the S1 superbubble shell. The interstellar radiation field at the Sun appears to be harder than the field ionizing ambient diffuse gas, which may be a consequence of the low opacity of the tiny cloud surrounding the heliosphere. The spatial context of the Local Bubble is consistent with our location in the Orion spur.Comment: "From the Outer Heliosphere to the Local Bubble", held at International Space Sciences Institute, October 200

Reply to Martinez-Garcia et al. and to Abreu and Punjabi

Abstract not availableBastien Lechat, Ph.D., Peter Catcheside, Ph.D. Amy Reynolds, Ph.D. Robert J. Adams, M.D. R. Doug McEvoy, M.D. Danny J. Eckert, Ph.D

Developmental changes in word recognition threshold from two to five years of age in children with different middle ear status

The aims were to: (1) provide word recognition thresholds (WRTs) at 31, 43, and 61 months of age; (2) investigate developmental changes over time; (3) investigate the relationship between OME and WRT, and (4) investigate the relationship between WRT and hearing thresholds. Around 1000 children were tested longitudinally as part of the ALSPAC study, using an adaptive measure of word recognition in quiet. Mean WRTs were 28, 23, and 23 dB (A) at 31, 43, and 61 months, respectively. Normal auditory development is associated with a mean improvement in WRT of 5 dB between age 31 and 61 months. There was a mean increase in WRT of 5 dB and 15 dB when OME was present in one and two ears, respectively. Thus, both unilateral and bilateral OME results in a detrimental effect on hearing ability for speech. Additionally, early and ‘persistent’ OME is associated with greater disability. However by 61 months, previous OME status was not significant. To our knowledge, this is the largest longitudinal study reporting WRT in preschool children with different middle ear status

Ice-rich (periglacial) vs icy (glacial) depressions in the Argyre region, Mars: a proposed cold-climate dichotomy of landforms

On Mars, so-called “scalloped depressions” are widely observed in Utopia Planitia (UP) and Malea Planum (MP). Typically, they are rimless, metres- to decametres-deep, incised sharply, tiered inwardly, polygonised and sometimes pitted. The depressions seemingly incise terrain that is icy and possibly thermokarstic, i.e. produced by the thermal destabilisation of the icy terrain. Agewise, the depressions are thought to be relatively youthful, originating in the Late Amazonian Epoch.Here, we report the presence of similar depressions in the Argyre region (AR) (30–60° S; 290–355° E). More importantly, we separate and differentiate these landforms into two groups: (ice-rich) periglacial depressions (Type-1); and, (icy) glacial depressions (Type-2a-c). This differentiation is presented to the Mars community for the first time.Based on a suite of morphological and geological characteristics synonymous with ice-complexes in the Lena Peninsula (eastern Russia) and the Tuktoyaktuk Coastlands (Northwest Territories, Canada), we propose that the Type-1 depressions are ice-rich periglacial basins that have undergone volatile depletion largely by sublimation and as the result of thermal destabilisation. In keeping with the terms and associated definitions derived of terrestrial periglacial-geomorphology, ice-rich refers to permanently frozen-ground in which ice lenses or segregation ice (collectively referenced as excess ice) have formed.We suggest that the depressions are the product of a multi-step, cold-climate geochronology:(1) Atmospheric precipitation and surface accumulation of an icy mantle during recent high obliquities.(2) Regional or local triple-point conditions and thaw/evaporation of the mantle, either by exogenic forcing, i.e. obliquity-driven rises of aerial and sub-aerial temperatures, or endogenic forcing, i.e. along Argyre impact-related basement structures.(3) Meltwater migration into the regolith, at least to the full depth of the depressions.(4) Freeze-thaw cycling and the formation of excess ice.(5) Sublimation of the excess ice and depression formation as high obliquity dissipates and near-surface ice becomes unstable.The Type-2 depressions exhibit characteristics suggestive of (supra-glacial) dead-ice basins and snow/ice suncups observed in high-alpine landscapes on Earth, e.g. the Swiss Alps and the Himalayas. Like the Type-1 depressions, the Type-2 depressions could be the work of sublimation; however, the latter differ from the former in that they seem to develop within a glacial-like icy mantle that blankets the surface rather than within an ice-rich and periglacially-revised regolith at/near the surface.Interestingly, the Type-2 depressions overlie the Type-1 depressions at some locations. If the periglacial/glacial morphological and stratigraphical dichotomy of depressions is valid, then this points to recent glaciation at some locations within the AR being precursed by at least one episode of periglaciation. This also suggests that periglaciation has a deeper history in the region than has been thought hitherto. Moreover, if the hypothesised differences amongst the Argyre-based depressions are mirrored in Utopia Planitia and Malea Planum, then perhaps this periglacial-glacial dichotomy and its associated geochronology are as relevant to understanding late period landscape-evolution in these two regions as it is in the AR

Structure of SPH (Self-Incompatibility Protein Homologue) Proteins: a Widespread Family of Small, Highly Stable, Secreted Proteins

SPH proteins are a large family of small, disulphide-bonded, secreted proteins, initially found in the self-incompatibility response in the field poppy , but now known to be widely distributed in plants, many containing multiple members of this protein family. Using the Origami strain of , we expressed one member of this family, SPH15 from , as a folded thioredoxin-fusion protein and purified it from the cytosol. The fusion protein was cleaved and characterised by analytical ultracentrifugation, circular dichroism, and NMR spectroscopy. This showed that SPH15 is monomeric and temperature stable, with a beta-sandwich structure. The four strands in each sheet have the same topology as the unrelated proteins; human transthyretin, bacterial TSSJ, and pneumolysin, with no discernable sequence similarity. The NMR-derived structure was compared with a model, made using a new deep learning algorithm based on co-evolution/correlated mutations, DeepCDPred, validating the method. The DeepCDPred method and homology modelling to SPH15 were then both used to derive models of the 3D structure of the three known PrsS proteins from , which have only 15-18% sequence homology to SPH15. The DeepCDPred method gave models with lower Discreet Optimised Protein Energy (DOPE) scores than the homology models. Three loops at one end of the poppy structures are postulated to interact with their respective pollen receptors to instigate programmed cell death in pollen tubes. [Abstract copyright: ©2019 The Author(s).