The Quiet-Sun Photosphere and Chromosphere

The overall structure and the fine structure of the solar photosphere outside active regions are largely understood, except possibly important roles of a turbulent near-surface dynamo at its bottom, internal gravity waves at its top, and small-scale vorticity. Classical 1D static radiation-escape modelling has been replaced by 3D time-dependent MHD simulations that come closer to reality. The solar chromosphere, in contrast, remains ill-understood although its pivotal role in coronal mass and energy loading makes it a principal research area. Its fine structure defines its overall structure, so that hard-to-observe and hard-to-model small-scale dynamical processes are the key to understanding. However, both chromospheric observation and chromospheric simulation presently mature towards the required sophistication. The open-field features seem of greater interest than the easier-to-see closed-field features.Comment: Accepted for special issue "Astrophysical Processes on the Sun" of Phil. Trans. Royal Soc. A, ed. C. Parnell. Note: clicking on the year in a citation opens the corresponding ADS abstract page in the browse

Coinductive interpreters for process calculi

This paper suggests functional programming languages with coinductive types as suitable devices for prototyping process calculi. The proposed approach is independent of any particular process calculus and makes explicit the different ingredients present in the design of any such calculi. In particular structural aspects of the underlying behaviour model (e.g. the dichotomies such as active vs reactive, deterministic vs nondeterministic) become clearly separated from the interaction structure which defines the synchronisation discipline. The approach is illustrated by the detailed development in Charity of an interpreter for a family of process languages.(undefined

Aperture Increase Options for the Dutch Open Telescope

This paper is an invitation to the international community to participate in the usage and a substantial upgrade of the Dutch Open Telescope on La Palma (DOT, \url{http://dot.astro.uu.nl}). We first give a brief overview of the approach, design, and current science capabilities of the DOT. The DOT database (\url{http://dotdb.phys.uu.nl/DOT}) now contains many tomographic image sequences with 0.2-0.3 arcsec resolution and up to multi-hour duration. You are welcome to pull them over for analysis. The main part of this contribution outlines DOT upgrade designs implementing larger aperture. The motivation for aperture increase is the recognition that optical solar physics needs the substantially larger telescope apertures that became useful with the advent of adaptive optics and viable through the DOT's open principle, both for photospheric polarimetry at high resolution and high sensitivity and for chromospheric fine-structure diagnosis at high cadence and full spectral sampling. Realization of an upgrade requires external partnership(s). This report about DOT upgrade options therefore serves also as initial documentation for potential partners.Comment: in press,"Physics of Chromospheric Plasmas" (Coimbra), ASP 368, 573 (2007

HST Observations of Chromospheres in Metal Deficient Field Giants

HST high resolution spectra of metal-deficient field giants more than double the stars in previous studies, span about 3 magnitudes on the red giant branch, and sample an abundance range [Fe/H]= -1 to -3. These stars, in spite of their age and low metallicity, possess chromospheric fluxes of Mg II (2800 Angstrom) that are within a factor of 4 of Population I stars, and give signs of a dependence on the metal abundance at the lowest metallicities. The Mg II k-line widths depend on luminosity and correlate with metallicity. Line profile asymmetries reveal outflows that occur at lower luminosities (M_V = -0.8) than detected in Ca K and H-alpha lines in metal-poor giants, suggesting mass outflow occurs over a larger span of the red giant branch than previously thought, and confirming that the Mg II lines are good wind diagnostics. These results do not support a magnetically dominated chromosphere, but appear more consistent with some sort of hydrodynamic, or acoustic heating of the outer atmospheres.Comment: 36 pages, 12 figures, 7 tables, and accepted for publication in The Astronomical Journa

An International Ultraviolet Explorer Archival Study of Dwarf Novae in Outburst

We present a synthetic spectral analysis of nearly the entire far ultraviolet International Ultraviolet Explorer (IUE) archive of spectra of dwarf novae in or near outburst. The study includes 46 systems of all dwarf nova subtypes both above and below the period gap. The spectra were uniformly analyzed using synthetic spectral codes for optically thick accretion disks and stellar photospheres along with the best-available distance measurements or estimates. We present newly estimated accretion rates and discuss the implications of our study for disk accretion physics and CV evolution.Comment: Accepted for publication in the ApJ, Part

Immune response profiles of calves following vaccination with live BCG and inactivated Mycobacterium bovis vaccine candidates

<div><p>Conventional control and eradication strategies for bovine tuberculosis (BTB) face tremendous difficulties in developing countries; countries with wildlife reservoirs, a complex wildlife-livestock-human interface or a lack of veterinary and veterinary public health surveillance. Vaccination of cattle and other species might in some cases provide the only suitable control strategy for BTB, while in others it may supplement existing test-and-slaughter schemes. However, the use of live BCG has several limitations and the global rise of HIV/AIDS infections has furthermore warranted the exploration of inactivated vaccine preparations. The aim of this study was to compare the immune response profiles in response to parenteral vaccination with live BCG and two inactivated vaccine candidates in cattle.</p><p>Twenty-four mixed breed calves (<i>Bos taurus</i>) aged 4–6 months, were allocated to one of four groups and vaccinated sub-cutaneously with live <i>M</i>. <i>bovis</i> BCG (Danish 1331), formalin-inactivated <i>M</i>. <i>bovis</i> BCG, heat-killed <i>M</i>. <i>bovis</i> or PBS/Montanide™ (control). Interferon-γ responsiveness and antibody production were measured prior to vaccination and at weekly intervals thereafter for twelve weeks. At nine weeks post-priming, animals were skin tested using tuberculins and MTBC specific protein cocktails and subsequently challenged through intranodular injection of live <i>M</i>. <i>bovis</i> BCG.</p><p>The animals in the heat-killed <i>M</i>. <i>bovis</i> group demonstrated strong and sustained cell-mediated and humoral immune responses, significantly higher than the control group in response to vaccination, which may indicate a protective immune profile. Animals in this group showed reactivity to the skin test reagents, confirming good vaccine take. Lastly, although not statistically significant, recovery of BCG after challenge was lowest in the heat-killed <i>M</i>. <i>bovis</i> group.</p><p>In conclusion, the parenteral heat-killed <i>M</i>. <i>bovis</i> vaccine proved to be clearly immunogenic in cattle in the present study, urging further evaluation of the vaccine in challenge studies using virulent <i>M</i>. <i>bovis</i> and assessment of vaccine efficacy in field conditions.</p></div

Lifestyle coaches as a central professional in the health care network?:Dynamic changes over time using a network analysis

BackgroundOverweight and obesity are problems that are increasing globally in both children as well as adults, and may be prevented by adopting a healthier lifestyle. Lifestyle coaches counsel overweight and obese children (and their parents) as well as adults in initiating and maintaining healthier lifestyle behaviours. It is currently unclear whether this novel professional in the Dutch health care system functions as a linchpin in networks that evolve around lifestyle-related health problems. The aim of the present study is to investigate the formation and development of networks of lifestyle coaches and their positions within these networks.MethodsIn this longitudinal study, key professionals and professionals within relevant organisations in the Coaching on Lifestyle (CooL) care networks were asked to fill in three online questionnaires. Respondents were asked to indicate whether they collaborated with each of the specified professionals in the context of CooL. The overall network structures and the central role of the lifestyle coaches were examined by using network analysis.ResultsThe results showed that the networks in three out of four regions were relatively centralised, but that none of the networks were dense, and that the professionals seemed to collaborate less with others over time. Half of the lifestyle coaches had a high number of collaborations and a central position within their networks, which also increased over time. In half of the regions, the lifestyle coaches had increased their role as consultants, while their role as gatekeeper and liaison decreased over time. In most regions, the sector of lifestyle coaches had a central position in their networks in just one measurement. Other central sectors were the local sports organisation, public health services, youth health care and the municipal government.ConclusionsOverall, we cannot conclude that more central and denser networks were formed during the study period. In addition, the lifestyle coaches were not often positioned as a central sector within these networks. Entrepreneurial, network and brokering competences are required for lifestyle coaches to build up denser networks.Trial registrationNTR6208; date registered: 13-01-2017; retrospectively registered; Netherlands Trial Register

A Far-Ultraviolet Spectroscopic Survey of Luminous Cool Stars

FUSE ultraviolet spectra of 8 giant and supergiant stars reveal that high temperature (3 X 10^5 K) atmospheres are common in luminous cool stars and extend across the color-magnitude diagram from Alpha Car (F0 II) to the cool giant Alpha Tau (K5 III). Emission present in these spectra includes chromospheric H-Lyman Beta, Fe II, C I, and transition region lines of C III, O VI, Si III, Si IV. Emission lines of Fe XVIII and Fe XIX signaling temperatures of ~10^7 K and coronal material are found in the most active stars, Beta Cet and 31 Com. A short-term flux variation, perhaps a flare, was detected in Beta Cet during our observation. Stellar surface fluxes of the emission of C III and O VI are correlated and decrease rapidly towards the cooler stars, reminiscent of the decay of magnetically-heated atmospheres. Profiles of the C III (977A) lines suggest that mass outflow is underway at T~80,000 K, and the winds are warm. Indications of outflow at higher temperatures (3 X 10^5K) are revealed by O VI asymmetries and the line widths themselves. High temperature species are absent in the M-supergiant Alpha Ori. Narrow fluorescent lines of Fe II appear in the spectra of many giants and supergiants, apparently pumped by H Lyman Alpha, and formed in extended atmospheres. Instrumental characteristics that affect cool star spectra are discussed.Comment: Accept for publication in The Astrophysical Journal; 22 pages of text, 23 figures and 8 table