5,231 research outputs found
Experimental conditions to suppress edge localised modes by magnetic perturbations in the ASDEX Upgrade tokamak
Access conditions for full suppression of Edge Localised Modes (ELMs) by
Magnetic Perturbations (MP) in low density high confinement mode (H-mode)
plasmas are studied in the ASDEX Upgrade tokamak. The main empirical
requirements for full ELM suppression in our experiments are: 1. The poloidal
spectrum of the MP must be aligned for best plasma response from weakly stable
kink-modes, which amplify the perturbation, 2. The plasma edge density must be
below a critical value, ~m. The edge collisionality
is in the range (ions) and
(electrons). However, our data does not show that the edge collisionality is
the critical parameter that governs access to ELM suppression. 3. The pedestal
pressure must be kept sufficiently low to avoid destabilisation of small ELMs.
This requirement implies a systematic reduction of pedestal pressure of
typically 30\% compared to unmitigated ELMy H-mode in otherwise similar
plasmas. 4. The edge safety factor lies within a certain window.
Within the range probed so far, , one such window,
has been identified. Within the range of plasma rotation
encountered so far, no apparent threshold of plasma rotation for ELM
suppression is found. This includes cases with large cross field electron flow
in the entire pedestal region, for which two-fluid MHD models predict that the
resistive plasma response to the applied MP is shielded
Quantification of Hair Cortisol Concentration in Common Marmosets (\u3cem\u3eCallithrix jacchus\u3c/em\u3e) and Tufted Capuchins (\u3cem\u3eCebus apella\u3c/em\u3e)
Quantifying cortisol concentration in hair is a non-invasive biomarker of long-term hypothalamic-pituitary-adrenal (HPA) activation, and thus can provide important information on laboratory animal health. Marmosets (Callithrix jacchus) and capuchins (Cebus apella) are New World primates increasingly used in biomedical and neuroscience research, yet published hair cortisol concentrations for these species are limited. Review of the existing published hair cortisol values from marmosets reveals highly discrepant values and the use of variable techniques for hair collection, processing, and cortisol extraction. In this investigation we utilized a well-established, standardized protocol to extract and quantify cortisol from marmoset (n = 12) and capuchin (n = 4) hair. Shaved hair samples were collected from the upper thigh during scheduled exams and analyzed via methanol extraction and enzyme immunoassay. In marmosets, hair cortisol concentration ranged from 2710 â 6267 pg/mg and averaged 4070 ± 304 pg/mg. In capuchins, hair cortisol concentration ranged from 621 â 2089 pg/mg and averaged 1092 ± 338 pg/mg. Hair cortisol concentration was significantly different between marmosets and capuchins, with marmosets having higher concentrations than capuchins. The incorporation of hair cortisol analysis into research protocols provides a non-invasive measure of HPA axis activity over time, which offers insight into animal health. Utilization of standard protocols across laboratories is essential to obtaining valid measurements and allowing for valuable future cross-species comparisons
Outlying HII Regions in HI-Selected Galaxies
We present results from the first systematic search for outlying HII regions,
as part of a sample of 96 emission-line point sources (referred to as ELdots -
emission-line dots) derived from the NOAO Survey for Ionization in Neutral Gas
Galaxies (SINGG). Our automated ELdot-finder searches SINGG narrow-band and
continuum images for high equivalent width point sources outside the optical
radius of the target galaxy (> 2 X r25 in the R-band). Follow-up longslit
spectroscopy and deep GALEX images (exposure time > 1000 s) distinguish
outlying HII regions from background galaxies whose strong emission lines
([OIII], Hbeta or [OII]) have been redshifted into the SINGG bandpass. We find
that these deep GALEX images can serve as a substitute for spectroscopic
follow-up because outlying HII regions separate cleanly from background
galaxies in color-color space. We identify seven SINGG systems with outlying
massive star formation that span a large range in Halpha luminosities
corresponding to a few O stars in the most nearby cases, and unresolved dwarf
satellite companion galaxies in the most distant cases. Six of these seven
systems feature galaxies with nearby companions or interacting galaxies.
Furthermore, our results indicate that some outlying HII regions are linked to
the extended-UV disks discovered by GALEX, representing emission from the most
massive O stars among a more abundant population of lower mass (or older) star
clusters. The overall frequency of outlying HII regions in this sample of
gas-rich galaxies is 8 - 11% when we correct for background emission-line
galaxy contamination (~75% of ELdots).Comment: 20 pages, 14 Figures, Accepted by A
The Role of Deontic Logic in the Specification of Information Systems
In this paper we discuss the role that deontic logic plays in the specification of information systems, either because constraints on the systems directly concern norms or, and even more importantly, system constraints are considered ideal but violable (so-called `softÂż constraints).\ud
To overcome the traditional problems with deontic logic (the so-called paradoxes), we first state the importance of distinguishing between ought-to-be and ought-to-do constraints and next focus on the most severe paradox, the so-called Chisholm paradox, involving contrary-to-duty norms. We present a multi-modal extension of standard deontic logic (SDL) to represent the ought-to-be version of the Chisholm set properly. For the ought-to-do variant we employ a reduction to dynamic logic, and show how the Chisholm set can be treated adequately in this setting. Finally we discuss a way of integrating both ought-to-be and ought-to-do reasoning, enabling one to draw conclusions from ought-to-be constraints to ought-to-do ones, and show by an example the use(fulness) of this
Intergalactic HII Regions Discovered in SINGG
A number of very small isolated HII regions have been discovered at projected
distances up to 30 kpc from their nearest galaxy. These HII regions appear as
tiny emission line objects in narrow band images obtained by the NOAO Survey
for Ionization in Neutral Gas Galaxies (SINGG). We present spectroscopic
confirmation of four isolated HII regions in two systems, both systems have
tidal HI features. The results are consistent with stars forming in interactive
debris due to cloud-cloud collisions. The H-alpha luminosities of the isolated
HII regions are equivalent to the ionizing flux of only a few O stars each.
They are most likely ionized by stars formed in situ, and represent atypical
star formation in the low density environment of the outer parts of galaxies. A
small but finite intergalactic star formation rate will enrich and ionize the
surrounding medium. In one system, NGC 1533, we calculate a star formation rate
of 1.5e-3 msun/yr, resulting in a metal enrichment of ~1e-3 solar for the
continuous formation of stars. Such systems may have been more common in the
past and a similar enrichment level is measured for the `metallicity floor' in
damped Lyman-alpha absorption systems.Comment: accepted for publication in the Astronomical Journal, 19 pages,
including 5 figures, some low resolution. Paper with high resolution images
can be downloaded from
http://astro.ph.unimelb.edu.au/~eryan/publications/eldots.ps.g
The Survey for Ionization in Neutral Gas Galaxies- II. The Star Formation Rate Density of the Local Universe
We derive observed Halpha and R band luminosity densities of an HI-selected
sample of nearby galaxies using the SINGG sample to be l_Halpha' = (9.4 +/-
1.8)e38 h_70 erg s^-1 Mpc^-3 for Halpha and l_R' = (4.4 +/- 0.7)e37 h_70 erg
s^-1 A^-1 Mpc^-3 in the R band. This R band luminosity density is approximately
70% of that found by the Sloan Digital Sky Survey. This leads to a local star
formation rate density of log(SFRD) = -1.80 +0.13/-0.07(random) +/-
0.03(systematic) + log(h_70) after applying a mean internal extinction
correction of 0.82 magnitudes. The gas cycling time of this sample is found to
be t_gas = 7.5 +1.3/-2.1 Gyr, and the volume-averaged equivalent width of the
SINGG galaxies is EW(Halpha) = 28.8 +7.2/-4.7 A (21.2 +4.2/-3.5 A without
internal dust correction). As with similar surveys, these results imply that
SFRD(z) decreases drastically from z ~ 1.5 to the present. A comparison of the
dynamical masses of the SINGG galaxies evaluated at their optical limits with
their stellar and HI masses shows significant evidence of downsizing: the most
massive galaxies have a larger fraction of their mass locked up in stars
compared with HI, while the opposite is true for less massive galaxies. We show
that the application of the Kennicutt star formation law to a galaxy having the
median orbital time at the optical limit of this sample results in a star
formation rate decay with cosmic time similar to that given by the SFRD(z)
evolution. This implies that the SFRD(z) evolution is primarily due to the
secular evolution of galaxies, rather than interactions or mergers. This is
consistent with the morphologies predominantly seen in the SINGG sample.Comment: 15 pages, 5 figures, ApJ in press. Data available at
http://sungg.pha.jhu.edu/PubData/ Corrected: Minor typos and formatting
issues fixe
Comparison of Winter Strawberry Production in a Commercial Heated High Tunnel versus a University Greenhouse
For the past 4 years, the University of Nebraska strawberry team has worked to develop low cost, sustainable methods for farmers and growers to produce strawberries in a double polyethylene greenhouse during the winter. This past year, this growing system was adapted to become a commercial growerâs heated high tunnel for the winter/spring of 2013-14. The idea was to scale up to a farm-size demonstration and compare it to the university greenhouse production system with a goal to expand marketing opportunities for strawberries into the winter season
Tracheotomy care simulation training program for inpatient providers
Objectives: Tracheotomy complications can be life-threatening. Many of these complications may be avoided with proper education of health care providers. Unfortunately, access to high-quality tracheotomy care curricula is limited. We developed a program to address this gap in tracheotomy care education for inpatient providers. This study aimed to assess the efficacy of this training program in improving trainee knowledge and comfort with tracheotomy care.
Methods: The curriculum includes asynchronous online modules coupled with a self-directed hands-on simulation activity using a low-cost tracheotomy care task trainer. The program was offered to inpatient providers including medical students, residents, medical assistants, nurses, and respiratory therapists. Efficacy of the training was assessed using pre-training and post-training surveys of learner comfort, knowledge, and qualitative feedback.
Results: Data was collected on 41 participants. After completing the program, participants exhibited significantly improved comfort in performing tracheotomy care activities and 15% improvement in knowledge scores, with large effect sizes respectively and greater gains among those with little prior tracheotomy care experience.
Conclusion: This study has demonstrated that completion of this integrated online and hands-on tracheotomy simulation curriculum training increases comfort and knowledge, especially for less-experienced learners. This training addresses an important gap in tracheotomy care education among health care professionals with low levels of tracheotomy care experience and ultimately aims to improve patient safety and quality of care. This curriculum is easily transferrable as it requires only access to the online modules and low-cost simulation materials and could be used in other hospitals, long-term care facilities, outpatient clinics, and home settings
The Survey for Ionization in Neutral Gas Galaxies: I. Description and Initial Results
We introduce the Survey for Ionization in Neutral Gas Galaxies (SINGG), a
census of star formation in HI-selected galaxies. The survey consists of
H-alpha and R-band imaging of a sample of 468 galaxies selected from the HI
Parkes All Sky Survey (HIPASS). The sample spans three decades in HI mass and
is free of many of the biases that affect other star forming galaxy samples. We
present the criteria for sample selection, list the entire sample, discuss our
observational techniques, and describe the data reduction and calibration
methods. This paper focuses on 93 SINGG targets whose observations have been
fully reduced and analyzed to date. The majority of these show a single
Emission Line Galaxy (ELG). We see multiple ELGs in 13 fields, with up to four
ELGs in a single field. All of the targets in this sample are detected in
H-alpha indicating that dormant (non-star forming) galaxies with M(HI) > ~3e7
M_sun are very rare. A database of the measured global properties of the ELGs
is presented. The ELG sample spans four orders of magnitude in luminosity
(H-alpha and R-band), and H-alpha surface brightness, nearly three orders of
magnitude in R surface brightness and nearly two orders of magnitude in H-alpha
equivalent width (EW). The surface brightness distribution of our sample is
broader than that of the Sloan Digital Sky Survey spectroscopic sample, the
(EW) distribution is broader than prism-selected samples, and the morphologies
found include all common types of star forming galaxies (e.g. irregular,
spiral, blue compact dwarf, starbursts, merging and colliding systems, and even
residual star formation in S0 and Sa spirals). (abridged)Comment: 28 pages, ApJS, in press. Full resolution version with all panels of
Fig. 8 available at http://sungg.pha.jhu.edu/publications.html . On line data
available at http://sungg.pha.jhu.edu/PubData/ . Author list corrected. Wrong
value for f_ap used in eq. 7 now corrected; typos corrected, non-used
references replaced, others update
Type IIb Supernova SN 2011dh: Spectra and Photometry from the Ultraviolet to the Near-Infrared
We report spectroscopic and photometric observations of the Type IIb SN
2011dh obtained between 4 and 34 days after the estimated date of explosion
(May 31.5 UT). The data cover a wide wavelength range from 2,000 Angstroms in
the UV to 2.4 microns in the NIR. Optical spectra provide line profiles and
velocity measurements of HI, HeI, CaII and FeII that trace the composition and
kinematics of the SN. NIR spectra show that helium is present in the atmosphere
as early as 11 days after the explosion. A UV spectrum obtained with the STIS
reveals that the UV flux for SN 2011dh is low compared to other SN IIb. The HI
and HeI velocities in SN 2011dh are separated by about 4,000 km/s at all
phases. We estimate that the H-shell of SN 2011dh is about 8 times less massive
than the shell of SN 1993J and about 3 times more massive than the shell of SN
2008ax. Light curves (LC) for twelve passbands are presented. The maximum
bolometric luminosity of erg s occurred
about 22 days after the explosion. NIR emission provides more than 30% of the
total bolometric flux at the beginning of our observations and increases to
nearly 50% of the total by day 34. The UV produces 16% of the total flux on day
4, 5% on day 9 and 1% on day 34. We compare the bolometric light curves of SN
2011dh, SN 2008ax and SN 1993J. The LC are very different for the first twelve
days after the explosions but all three SN IIb display similar peak
luminosities, times of peak, decline rates and colors after maximum. This
suggests that the progenitors of these SN IIb may have had similar compositions
and masses but they exploded inside hydrogen shells that that have a wide range
of masses. The detailed observations presented here will help evaluate
theoretical models for this supernova and lead to a better understanding of SN
IIb.Comment: 23 pages, 14 figures, 9 tables, accepted by Ap
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