1,360 research outputs found
Chemical species concentration measurement via wireless sensors
This paper describes studies carried out to investigate the viability of using wireless cameras as a tool in monitoring changes in air quality. A camera is used to monitor the change in colour of a chemically responsive polymer within view of the camera as it is exposed to varying chemical species concentration levels. The camera captures this image and the colour change is analyzed by averaging the RGB values present. This novel chemical sensing approach is compared with an established chemical sensing method using the same chemically responsive polymer coated onto LEDs. In this way, the concentration levels of acetic acid in the air can be tracked using both approaches. These approaches to chemical plume tracking have many applications for air quality monitoring
Simulating Radiating and Magnetized Flows in Multi-Dimensions with ZEUS-MP
This paper describes ZEUS-MP, a multi-physics, massively parallel, message-
passing implementation of the ZEUS code. ZEUS-MP differs significantly from the
ZEUS-2D code, the ZEUS-3D code, and an early "version 1" of ZEUS-MP distributed
publicly in 1999. ZEUS-MP offers an MHD algorithm better suited for
multidimensional flows than the ZEUS-2D module by virtue of modifications to
the Method of Characteristics scheme first suggested by Hawley and Stone
(1995), and is shown to compare quite favorably to the TVD scheme described by
Ryu et. al (1998). ZEUS-MP is the first publicly-available ZEUS code to allow
the advection of multiple chemical (or nuclear) species. Radiation hydrodynamic
simulations are enabled via an implicit flux-limited radiation diffusion (FLD)
module. The hydrodynamic, MHD, and FLD modules may be used in one, two, or
three space dimensions. Self gravity may be included either through the
assumption of a GM/r potential or a solution of Poisson's equation using one of
three linear solver packages (conjugate-gradient, multigrid, and FFT) provided
for that purpose. Point-mass potentials are also supported. Because ZEUS-MP is
designed for simulations on parallel computing platforms, considerable
attention is paid to the parallel performance characteristics of each module.
Strong-scaling tests involving pure hydrodynamics (with and without
self-gravity), MHD, and RHD are performed in which large problems (256^3 zones)
are distributed among as many as 1024 processors of an IBM SP3. Parallel
efficiency is a strong function of the amount of communication required between
processors in a given algorithm, but all modules are shown to scale well on up
to 1024 processors for the chosen fixed problem size.Comment: Accepted for publication in the ApJ Supplement. 42 pages with 29
inlined figures; uses emulateapj.sty. Discussions in sections 2 - 4 improved
per referee comments; several figures modified to illustrate grid resolution.
ZEUS-MP source code and documentation available from the Laboratory for
Computational Astrophysics at http://lca.ucsd.edu/codes/currentcodes/zeusmp2
The Lyman Alpha Reference Sample. VIII. Characterizing Lyman-Alpha Scattering in Nearby Galaxies
We examine the dust geometry and Ly{\alpha} scattering in the galaxies of the
Lyman Alpha Reference Sample (LARS), a set of 14 nearby (0.02 < < 0.2)
Ly{\alpha} emitting and starbursting systems with Hubble Space Telescope
Ly{\alpha}, H{\alpha}, and H{\beta} imaging. We find that the global dust
properties determined by line ratios are consistent with other studies, with
some of the LARS galaxies exhibiting clumpy dust media while others of them
show significantly lower Ly{\alpha} emission compared to their Balmer
decrement. With the LARS imaging, we present Ly{\alpha}/H{\alpha} and
H{\alpha}/H{\beta} maps with spatial resolutions as low as 40 pc, and
use these data to show that in most galaxies, the dust geometry is best modeled
by three distinct regions: a central core where dust acts as a screen, an
annulus where dust is distributed in clumps, and an outer envelope where
Ly{\alpha} photons only scatter. We show that the dust that affects the escape
of Ly{\alpha} is more restricted to the galaxies' central regions, while the
larger Ly{\alpha} halos are generated by scattering at large radii. We present
an empirical modeling technique to quantify how much Ly{\alpha} scatters in the
halo, and find that this "characteristic" scattering distance correlates with
the measured size of the Ly{\alpha} halo. We note that there exists a slight
anti-correlation between the scattering distance of Ly{\alpha} and global dust
properties.Comment: 32 pages, 51 figures, accepted to Ap
The Lyman Alpha Reference Sample: III. Properties of the Neutral ISM from GBT and VLA Observations
We present new H I imaging and spectroscopy of the 14 UV-selected
star-forming galaxies in the Lyman Alpha Reference Sample (LARS), aimed for a
detailed study of the processes governing the production, propagation, and
escape of Ly photons. New H I spectroscopy, obtained with the 100m
Green Bank Telescope (GBT), robustly detects the H I spectral line in 11 of the
14 observed LARS galaxies (although the profiles of two of the galaxies are
likely confused by other sources within the GBT beam); the three highest
redshift galaxies are not detected at our current sensitivity limits. The GBT
profiles are used to derive fundamental H I line properties of the LARS
galaxies. We also present new pilot H I spectral line imaging of 5 of the LARS
galaxies obtained with the Karl G. Jansky Very Large Array (VLA). This imaging
localizes the H I gas and provides a measurement of the total H I mass in each
galaxy. In one system, LARS 03 (UGC 8335 or Arp 238), VLA observations reveal
an enormous tidal structure that extends over 160 kpc from the main interacting
systems and that contains 10 M of H I. We compare various H I
properties with global Ly quantities derived from HST measurements. The
measurements of the Ly escape fraction are coupled with the new direct
measurements of H I mass and significantly disturbed H I velocities. Our
robustly detected sample reveals that both total H I mass and linewidth are
tentatively correlated with key Ly tracers. Further, on global scales,
these data support a complex coupling between Ly propagation and the H
I properties of the surrounding medium.Comment: Preprint form, 16 figures, accepted in Ap
Efficacy of depth jumps to elicit a post-activation performance enhancement in junior endurance runners
Objectives: To determine the effect of performing depth jumps (DJ) pre-exercise on running economy (RE) and time to exhaustion (TTE) at the speed associated with maximal oxygen uptake (sVËO2max) in a group of high-performing junior middle-distance runners. Design: Randomized crossover study. Methods: Seventeen national- and international-standard male distance runners (17.6 ± 1.2 years, 63.4 ± 6.3 kg, 1.76 ± 0.06 m, 70.7 ± 5.2 mL kgâ1 minâ1) completed two trials. Following a 5 min warm-up at 60% VËO2max, participants performed a 5 min run at 20%Î below oxygen uptake corresponding with lactate turn-point to determine pre-intervention RE. Participants then completed either six DJ from a box equivalent to their best counter-movement jump (CMJ) or a control condition (C) involving body weight quarter squats. After a 10 min passive recovery, another 5 min sub-maximal run was performed followed by a run to exhaustion at sVËO2max. Results: Compared to the C trial, DJ produced moderate improvements (â3.7%, 95% confidence interval for effect size: 0.25â1.09) in RE, which within the context of minimal detectable change is considered possibly beneficial. Differences in TTE and other physiological variables were most likely trivial (ES: <0.2). Individual responses were small, however a partial correlation revealed a moderate relationship (r = â0.55, p = 0.028) between change in RE and CMJ height. Conclusions: The inclusion of a set of six DJ in the warm-up routine of a well-trained young male middle-distance runner is likely to provide a moderate improvement in RE
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Contextualized analysis of a needs assessment using the Theoretical Domains Framework: a case example in endocrinology
Background: The Theoretical Domains Framework (TDF) is a set of 14 domains of behavior change that provide a framework for the critical issues and factors influencing optimal knowledge translation. Considering that a previous study has identified optimal knowledge translation techniques for each TDF domain, it was hypothesized that the TDF could be used to contextualize and interpret findings from a behavioral and educational needs assessment. To illustrate this hypothesis, findings and recommendations drawn from a 2012 national behavioral and educational needs assessment conducted with healthcare providers who treat and manage Growth and Growth Hormone Disorders, will be discussed using the TDF. Methods: This needs assessment utilized a mixed-methods research approach that included a combination of: [a] data sources (Endocrinologists (n:120), Pediatric Endocrinologists (n:53), Pediatricians (n:52)), [b] data collection methods (focus groups, interviews, online survey), [c] analysis methodologies (qualitative - analyzed through thematic analysis, quantitative - analyzed using frequencies, cross-tabulations, and gap analysis). Triangulation was used to generate trustworthy findings on the clinical practice gaps of endocrinologists, pediatric endocrinologists, and general pediatricians in their provision of care to adult patients with adult growth hormone deficiency or acromegaly, or children/teenagers with pediatric growth disorders. The identified gaps were then broken into key underlying determinants, categorized according to the TDF domains, and linked to optimal behavioral change techniques. Results: The needs assessment identified 13 gaps, each with one or more underlying determinant(s). Overall, these determinants were mapped to 9 of the 14 TDF domains. The Beliefs about Consequences domain was identified as a contributing determinant to 7 of the 13 challenges. Five of the gaps could be related to the Skills domain, while three were linked to the Knowledge domain. Conclusions: The TDF categorization of the needs assessment findings allowed recommendation of appropriate behavior change techniques for each underlying determinant, and facilitated communication and understanding of the identified issues to a broader audience. This approach provides a means for health education researchers to categorize gaps and challenges identified through educational needs assessments, and facilitates the application of these findings by educators and knowledge translators, by linking the gaps to recommended behavioral change techniques
The Lyman alpha reference sample. VII. Spatially resolved H kinematics
We present integral field spectroscopic observations with the Potsdam Multi
Aperture Spectrophotometer of all 14 galaxies in the Lyman Alpha
Reference Sample (LARS). We produce 2D line of sight velocity maps and velocity
dispersion maps from the Balmer (H) emission in our data
cubes. These maps trace the spectral and spatial properties of the LARS
galaxies' intrinsic Ly radiation field. We show our kinematic maps
spatially registered onto the Hubble Space Telescope H and Lyman
(Ly) images. Only for individual galaxies a causal connection
between spatially resolved H kinematics and Ly photometry can
be conjectured. However, no general trend can be established for the whole
sample. Furthermore, we compute non-parametric global kinematical statistics --
intrinsic velocity dispersion , shearing velocity ,
and the ratio -- from our kinematic maps. In
general LARS galaxies are characterised by high intrinsic velocity dispersions
(54\,km\,s median) and low shearing velocities (65\,km\,s
median). values range from 0.5 to 3.2 with an
average of 1.5. Noteworthy, five galaxies of the sample are dispersion
dominated systems with and are thus
kinematically similar to turbulent star forming galaxies seen at high redshift.
When linking our kinematical statistics to the global LARS Ly
properties, we find that dispersion dominated systems show higher Ly
equivalent widths and higher Ly escape fractions than systems with
. Our result indicates that turbulence in
actively star-forming systems is causally connected to interstellar medium
conditions that favour an escape of Ly radiation.Comment: 26 pages, 15 figures, accepted for publication in A&
Modelling hepatitis C infection acquired from blood transfusions in the UK between 1970 and 1991 for the Infected Blood Inquiry
The Statistics Expert Group was convened at the request of the Infected Blood Inquiry to provide estimates of the number of infections and deaths from blood-borne infections including hepatitis B virus, human immunodeficiency virus, hepatitis C virus (HCV) and variant Creutzfeldt Jakob disease, as a direct result of contaminated blood and blood products administered in the United Kingdom of Great Britain and Northern Ireland (UK). In the absence of databases of HCV infections and related deaths for all nations of the UK, a statistical model was required to estimate the number of infections and subsequent deaths from HCV acquired from blood transfusions from January 1970 to August 1991. We present this statistical model in detail alongside the results of its application to each of the four nations in the UK. We estimated that 26â800 people (95% uncertainty interval 21 300â38 800) throughout the UK were chronically infected with HCV because of contaminated blood transfusions between January 1970 and August 1991. The number of deaths up to the end of 2019 that occurred as a result of this chronic infection is estimated to be 1820 (95% uncertainty interval 650â3320)
Silent Phase of Johneâs Disease in Experimentally Infected Goats â A Study on New and Established Diagnostic Approaches Using Specific and Non-Specific Parameters
The current gold standard diagnostic test for Johneâs disease (JD) is detecting Mycobacterium avium subsp. paratuberculosis (MAP) from fecal samples via culture and/or PCR. Other commercially available JD diagnostic tests focus on the detection of specific antibodies within the serum or milk of infected ruminants. These tests have a high specificity but low their sensitivity and usually fail to diagnose the disease until later stages of the disease. The ideal diagnostic test should detect infected animals already during the silent phase. Here, we evaluate the use of new and established approaches to define the silent phase of JD in experimentally infected goats. None of the established diagnostic tests or new approaches for the detection of humoral and cellular immune responses were positive during the first year of infection. Only the characterization of various subsets of peripheral blood leukocytes and the weight development gave some indication for the presence of a chronic, but silent, infection. Weight differences were present throughout the first year. In addition, some of the subsets of leukocytes (WC1+ T cells, MHC class II+ leukocytes, CD1+ leukocytes, CD14+ granulocytes, and CD14+/MHC class II+ granulocytes) demonstrated significant differences, but only at certain time points
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