1,825 research outputs found
Development and testing of a mouse simulated space flight model
The development and testing of a mouse model for simulating some aspects of weightlessness that occurs during space flight, and the carrying out of immunological experiments on animals undergoing space flight is examined. The mouse model developed was an antiorthostatic, hypokinetic, hypodynamic suspension model similar to one used with rats. The study was divided into two parts. The first involved determination of which immunological parameters should be observed on animals flown during space flight or studied in the suspension model. The second involved suspending mice and determining which of those immunological parameters were altered by the suspension. Rats that were actually flown in Space Shuttle SL-3 were used to test the hypotheses
Response of lymphocytes to a mitogenic stimulus during spaceflight
Several studies were performed that demonstrate that immunological activities of lymphocytes can be affected by spaceflight or by models that attempt to simulate some aspects of weightlessness. Included among these are the responses of lymphocytes to external stimuli such as mitogens and viruses. When cultures of lymphocytes were flown in space, the ability of the lymphocytes to respond to mitogens was inhibited. Similar results were obtained when lymphocytes from astronauts or animals just returned from space were placed into culture immediately upon return to earth, and when models of hypogravity were used. Lymphocytes placed in culture during spaceflights produced enhanced levels of interferon compared to control cultures. When cultures of lymphocytes were prepared for cosmonauts or rodents immediately upon return to earth, interferon production was inhibited. These results suggest that space flight can have profound effects on lymphocyte function, and that effects on isolated cells may be different from that on cells in the whole organism
An HSC view of the CMASS galaxy sample. Halo mass as a function of stellar mass, size and S\'ersic index
Aims. We wish to determine the distribution of dark matter halo masses as a
function of the stellar mass and the stellar mass profile, for massive galaxies
in the BOSS CMASS sample. Methods. We use grizy photometry from HSC to obtain
S\'ersic fits and stellar masses of CMASS galaxies for which HSC weak lensing
data is available, visually selected to have spheroidal morphology. We apply a
cut in stellar mass, ,selecting 10, 000
objects. Using a Bayesian hierarchical inference method, we first investigate
the distribution of S\'ersic index and size as a function of stellar mass.
Then, making use of shear measurements from HSC, we measure the distribution of
halo mass as a function of stellar mass, size and S\'ersic index. Results. Our
data reveals a steep stellar mass-size relation ,
with larger than unity, and a positive correlation between S\'ersic
index and stellar mass: . Halo mass scales approximately
with the 1.7 power of the stellar mass. We do not find evidence for an
additional dependence of halo mass on size or S\'ersic index at fixed stellar
mass. Conclusions. Our results disfavour galaxy evolution models that predict
significant differences in the size growth efficiency of galaxies living in low
and high mass halos.Comment: Accepted for publication on Astronomy & Astrophysics. 18 pages, 15
figure
UV Absorptance of Titanium Dioxide Thin Films by Plasma Enhanced Deposition from Mixtures of Oxygen and Titanium-Tetrakis-Isopropoxide
A low pressure radio frequency discharge was used to deposit films by mixtures of oxygen and titanium (IV) isopropoxide (TTIP) at powers of 200W on films of polyethylene-terephthalat and samples of quartz glass. In the non-thermal plasma, films of rather pure TiO2 could be deposited as revealed by X-ray photo-electron spectroscopy. Besides the film growth rate and the chemical composition, the spectral behaviour of the spectral transmittance of visually transparent films was determined in the range from 200 to 500nm. Furthermore, the absorptance of films has been derived at characteristic spectral positions of the transmission spectra of the films. Accordingly, cut-off wavelength was found to increase with deposition time from 5 to 10min as well as with the concentration of TTIP in a range below 1.7%. At 310nm, the spectral absorption coefficient (extinction coefficient × concentration) was 12μm−1. While keeping other parameters constant, this coefficient decreased by 4μm−1 due to an increase of the concentration of TTIP from 1.7% to 8%. Simultaneously, the surface roughness increased as revealed by profilometry. Thus, since the chemical structure of films was found to change only marginally, a decrease of the film density is likely to cause the observed dependence of the absorption coefficient with increasing precursor concentratio
Using the Theory of Planned Behavior to Understand University Students Recycling Behavior
Improving recycling behavior is an important means to reducing the ever-increasing amount of waste sent to landfills. When discussing sustainable behaviors, such as recycling, the Theory of Planned Behavior (TPB) can be used to explain why people make the decisions they do. The Theory of Planned Behavior utilizes attitude, subjective norm and perceived behavioral control to be the predictors of behavioral intention. Once we can better explain why students decide to recycle or not to recycle we can utilize this data to increase recycling rates. The Theory of Planned Behavior was used as a basis for this study in order to uncover motivating factors related to on campus recycling. The results show that students have a positive attitude toward recycling on campus, they do not feel there is an established subjective norm to recycle on campus, and they feel in control of their ability to recycle on campus. The information provided from this research can be used to develop a more efficient recycling program and make revisions to current recycling strategies
Wprowadzenie
Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę
Statistical strong lensing. III. Inferences with complete samples of lenses
Context. Existing samples of strong lenses have been assembled by giving
priority to sample size, at the cost of having a complex selection function.
With the advent of the next generation of wide-field photometric surveys,
however, it might become possible to identify subsets of the lens population
with well-defined selection criteria, trading sample size for completeness.
Aims. There are two main advantages of working with a complete sample of
lenses. First, it is possible to recover the properties of the general
population of galaxies, of which strong lenses are a biased subset. Second, the
relative number of lenses and non-detections can be used to further constrain
models of galaxy structure. This work illustrates how to carry out a
statistical strong lensing analysis that takes advantage of these features.
Methods. I introduced a general formalism for the statistical analysis of a
sample of strong lenses with known selection function, then tested it on
simulated data. The simulation consists of a population of galaxies with
an axisymmetric power-law density profile, a population of background point
sources, and a subset of strong lenses, complete above an
observational cut.
Results. The method allows to recover the distribution in Einstein radius and
mass density slope of the galaxy population in an unbiased way. The number of
non-lenses helps to constrain the model when magnification data are not
available.
Conclusions. Complete samples of lenses are a powerful asset to turn precise
strong lensing measurements into accurate statements on the properties of the
general galaxy population.Comment: Submitted to Astronomy & Astrophysics. A 2-minute summary video is
available at https://youtu.be/f6PziIr9US
RingFinder: automated detection of galaxy-scale gravitational lenses in ground-based multi-filter imaging data
We present RingFinder, a tool for finding galaxy-scale strong gravitational
lenses in multiband imaging data. By construction, the method is sensitive to
configurations involving a massive foreground early-type galaxy and a faint,
background, blue source. RingFinder detects the presence of blue residuals
embedded in an otherwise smooth red light distribution by difference imaging in
two bands. The method is automated for efficient application to current and
future surveys, having originally been designed for the 150-deg2 Canada France
Hawaii Telescope Legacy Survey (CFHTLS). We describe each of the steps of
RingFinder. We then carry out extensive simulations to assess completeness and
purity. For sources with magnification mu>4, RingFinder reaches 42% (resp. 25%)
completeness and 29% (resp. 86%) purity before (resp. after) visual inspection.
The completeness of RingFinder is substantially improved in the particular
range of Einstein radii 0.8 < REin < 2. and lensed images brighter than g =
22.5, where it can be as high as 70%. RingFinder does not introduce any
significant bias in the source or deflector population. We conclude by
presenting the final catalog of RingFinder CFHTLS galaxy-scale strong lens
candidates. Additional information obtained with Hubble Space Telescope and
Keck Adaptive Optics high resolution imaging, and with Keck and Very Large
Telescope spectroscopy, is used to assess the validity of our classification,
and measure the redshift of the foreground and the background objects. From an
initial sample of 640,000 early type galaxies, RingFinder returns 2500
candidates, which we further reduce by visual inspection to 330 candidates. We
confirm 33 new gravitational lenses from the main sample of candidates, plus an
additional 16 systems taken from earlier versions of RingFinder. First
applications are presented in the SL2S galaxy-scale Lens Sample paper series.Comment: 32 pages (aastex 2col format), 6 figs, ApJ Accepte
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