1,087 research outputs found
Temperature dependence of ultraviolet absorption cross-sections of alternative hydrochlorofluorocarbons
Ultraviolet absorption cross-section of six alternative hydrochlorofluorocarbons (HCFC-21 HCFC-22, HCFC-123, HCFC-124, HCFC-141b and HCFC-142b1) have been measured between 170 and 260 nm for temperature ranging from 210 to 295 K. These data are compared with other available determinations performed at room temperature and their temperature dependence is discussed. Photodissociation coefficients are estimated and their temperature dependence is discussed. Impact of the photodissociation on the total atmospheric destruction of these compounds is illustrated
Ultraviolet absorption cross-sections of some carbonyl compounds and their temperature dependence
Ultraviolet absorption cross-section of phosgene (CCl2O), trichloroacetylchloride (CCl3-CClO) and trichloroacetaldehyde (CCl3-CHO) have been measured between 170 and 320 nm for temperature ranging from 210 to 295 K with classical double beam equipment. These data are compared with other available determinations performed at room temperature. Photodissociation coefficients are estimated and their temperature dependence is discussed. Impact of the photodissociation on the total atmospheric destruction of these compounds is illustrated
Deconvolution of Gas Diffusion Polarization in Ni/Gadolinium-Doped Ceria Fuel Electrodes
The deconvolution of physicochemical processes in impedance spectra of SOCs with nickel/ceria fuel electrodes is challenging as gas diffusion strongly overlaps with the electrochemical processes at fuel and air electrode. To overcome this issue, symmetrical cells were applied and the gas diffusion process at the fuel electrode was quantified by altering the inert component (nitrogen/helium) in a ternary fuel gas mixture. An effective gas transport parameter considering microstructural and geometrical features was derived, enabling a precise quantification of polarization resistances related to gas diffusion and hydrogen electrooxidation. The obtained values were applied to parameterize a dc cell model. The model validation in fuel cell and electrolyzer mode showed an excellent agreement between measured and simulated current/voltage characteristics over a wide range of technically meaningful gas compositions and operating temperatures
The impact of corporate philanthropy on reputation for corporate social performance
This study seeks to examine the mechanisms by which a corporation’s use of philanthropy affects its reputation for corporate social performance (CSP), which the authors conceive of as consisting of two dimensions: CSP awareness and CSP perception. Using signal detection theory (SDT), the authors model signal amplitude (the amount contributed), dispersion (number of areas supported), and consistency (presence of a corporate foundation) on CSP awareness and perception. Overall, this study finds that characteristics of firms' portfolio of philanthropic activities are a greater predictor of CSP awareness than of CSP perception. Awareness increases with signal amplitude, dispersion, and consistency. CSP perception is driven by awareness and corporate reputation. The authors’ contention that corporate philanthropy is a complex variable is upheld, as we find that CSP signal characteristics influence CSP awareness and perception independently and asymmetrically. The authors conclude by proposing avenues for future research
Juno: a Python-based graphical package for optical system design
This report introduces Juno, a modular Python package for optical design and
simulation. Juno consists of a complete library that includes a graphical user
interface to design and visualise arbitrary optical elements, set up wave
propagation simulations and visualise their results. To ensure an efficient
visualisation of the results, all simulation data are stored in a structured
database that can filter and sort the output. Finally, we present a practical
use case for Juno, where optical design and fabrication are interlaced in a
feedback cycle. The presented data show how to compare the simulated and the
measured propagation; if a difference or unexpected behaviour is found, we show
how to convert and import the optical element profile from a profilometer
measurement. The propagation through the profile can provide immediate feedback
about the quality of the element and a measure of the effects brought by
differences between the idealised and the actual profile, therefore, allowing
to exclude the experimental errors and to weigh every aspect of fabrication
errors.Comment: The software is available at https://github.com/DeMarcoLab/jun
Optimization of Apodized Pupil Lyot Coronagraph for ELTs
We study the optimization of the Apodized Pupil Lyot Coronagraph (APLC) in
the context of exoplanet imaging with ground-based telescopes. The APLC
combines an apodization in the pupil plane with a small Lyot mask in the focal
plane of the instrument. It has been intensively studied in the literature from
a theoretical point of view, and prototypes are currently being manufactured
for several projects. This analysis is focused on the case of Extremely Large
Telescopes, but is also relevant for other telescope designs.
We define a criterion to optimize the APLC with respect to telescope
characteristics like central obscuration, pupil shape, low order segment
aberrations and reflectivity as function of the APLC apodizer function and mask
diameter. Specifically, the method was applied to two possible designs of the
future European-Extremely Large Telescope (E-ELT).
Optimum configurations of the APLC were derived for different telescope
characteristics. We show that the optimum configuration is a stronger function
of central obscuration size than of other telescope parameters. We also show
that APLC performance is quite insensitive to the central obscuration ratio
when the APLC is operated in its optimum configuration, and demonstrate that
APLC optimization based on throughput alone is not appropriate.Comment: 9 pages, 17 figures, accepted for publication in Astronomy &
Astrophysic
Carbon Fiber Insoles Enhance Perception of Performance Despite Variable Objective Outcomes: Specific to the Moderately Active Individual
International Journal of Exercise Science 16(4): 885-897, 2023. Carbon fiber insoles (CFIs) may benefit performance in elite athletes, however, their use in moderately active individuals has been adopted without evidence supporting such enhancements in this population. Fifteen male subjects performed vertical jump (VJ) and repeat treadmill sprint tests before and after a VO2peak while wearing 1) CFIs and 2) control insoles (CON). Subjects completed a subjective survey regarding their perceived performance abilities for both conditions. There were no significant differences between CFIs and CON in VJ height, sprint distance, heart rate following sprints; and rate of oxygen consumption, perceived fatigue, and perceived exertion at 85% of maximal speed (p \u3e 0.05) during the VO2peak. At maximal speed, although there was no difference between conditions in peak rate of oxygen consumption (95%CI [-4.85, 0.21]) and respiratory exchange ratio (95%CI [-0.01, 0.03]), CFIs resulted in a reduced level of perceived fatigue (95%CI [-1, 0]) and perceived exertion (95%CI [-2, 0]) compared to CON. Subjects subjectively reported increased feelings of “propulsion or explosiveness” (p = 0.026) and being able to “perform better while jumping” (p = 0.029) while wearing CFIs. Heightened perceptions of performance enhancements when wearing CFIs indicate, in the moderately active, perceptual benefits could be more influential for determining CFI use
Comparison of coronagraphs for high contrast imaging in the context of Extremely Large Telescopes
We compare coronagraph concepts and investigate their behavior and
suitability for planet finder projects with Extremely Large Telescopes (ELTs,
30-42 meters class telescopes). For this task, we analyze the impact of major
error sources that occur in a coronagraphic telescope (central obscuration,
secondary support, low-order segment aberrations, segment reflectivity
variations, pointing errors) for phase, amplitude and interferometric type
coronagraphs. This analysis is performed at two different levels of the
detection process: under residual phase left uncorrected by an eXtreme Adaptive
Optics system (XAO) for a large range of Strehl ratio and after a general and
simple model of speckle calibration, assuming common phase aberrations between
the XAO and the coronagraph (static phase aberrations of the instrument) and
non-common phase aberrations downstream of the coronagraph (differential
aberrations provided by the calibration unit). We derive critical parameters
that each concept will have to cope with by order of importance. We evidence
three coronagraph categories as function of the accessible angular separation
and proposed optimal one in each case. Most of the time amplitude concepts
appear more favorable and specifically, the Apodized Pupil Lyot Coronagraph
gathers the adequate characteristics to be a baseline design for ELTs.Comment: 12 pages, 6 figures, Accepted for publication in A&
Principles guiding embryo selection following genome-wide haplotyping of preimplantation embryos.
STUDY QUESTION
How to select and prioritize embryos during PGD following genome-wide haplotyping?
SUMMARY ANSWER
In addition to genetic disease-specific information, the embryo selected for transfer is based on ranking criteria including the existence of mitotic and/or meiotic aneuploidies, but not carriership of mutations causing recessive disorders.
WHAT IS KNOWN ALREADY
Embryo selection for monogenic diseases has been mainly performed using targeted disease-specific assays. Recently, these targeted approaches are being complemented by generic genome-wide genetic analysis methods such as karyomapping or haplarithmisis, which are based on genomic haplotype reconstruction of cell(s) biopsied from embryos. This provides not only information about the inheritance of Mendelian disease alleles but also about numerical and structural chromosome anomalies and haplotypes genome-wide. Reflections on how to use this information in the diagnostic laboratory are lacking.
STUDY DESIGN, SIZE, DURATION
We present the results of the first 101 PGD cycles (373 embryos) using haplarithmisis, performed in the Centre for Human Genetics, UZ Leuven. The questions raised were addressed by a multidisciplinary team of clinical geneticist, fertility specialists and ethicists.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Sixty-three couples enrolled in the genome-wide haplotyping-based PGD program. Families presented with either inherited genetic variants causing known disorders and/or chromosomal rearrangements that could lead to unbalanced translocations in the offspring.
MAIN RESULTS AND THE ROLE OF CHANCE
Embryos were selected based on the absence or presence of the disease allele, a trisomy or other chromosomal abnormality leading to known developmental disorders. In addition, morphologically normal Day 5 embryos were prioritized for transfer based on the presence of other chromosomal imbalances and/or carrier information.
LIMITATIONS, REASONS FOR CAUTION
Some of the choices made and principles put forward are specific for cleavage-stage-based genetic testing. The proposed guidelines are subject to continuous update based on the accumulating knowledge from the implementation of genome-wide methods for PGD in many different centers world-wide as well as the results of ongoing scientific research.
WIDER IMPLICATIONS OF THE FINDINGS
Our embryo selection principles have a profound impact on the organization of PGD operations and on the information that is transferred among the genetic unit, the fertility clinic and the patients. These principles are also important for the organization of pre- and post-counseling and influence the interpretation and reporting of preimplantation genotyping results. As novel genome-wide approaches for embryo selection are revolutionizing the field of reproductive genetics, national and international discussions to set general guidelines are warranted.
STUDY FUNDING/COMPETING INTEREST(S)
The European Union's Research and Innovation funding programs FP7-PEOPLE-2012-IAPP SARM: 324509 and Horizon 2020 WIDENLIFE: 692065 to J.R.V., T.V., E.D. and M.Z.E. J.R.V., T.V. and M.Z.E. have patents ZL910050-PCT/EP2011/060211-WO/2011/157846 (‘Methods for haplotyping single cells’) with royalties paid and ZL913096-PCT/EP2014/068315-WO/2015/028576 (‘Haplotyping and copy-number typing using polymorphic variant allelic frequencies’) with royalties paid, licensed to Cartagenia (Agilent technologies). J.R.V. also has a patent ZL91 2076-PCT/EP20 one 3/070858 (‘High throughout genotyping by sequencing’) with royalties paid
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