502 research outputs found
Anti-inflammatory activity of Wnt signaling in enteric nervous system: in vitro preliminary evidences in rat primary cultures
Background: In the last years, Wnt signaling was demonstrated to regulate inflammatory processes. In particular, an increased expression of Wnts and Frizzled receptors was reported in inflammatory bowel disease (IBD) and ulcerative colitis to exert both anti- and pro-inflammatory functions regulating the intestinal activated nuclear factor \u3baB (NF-\u3baB), TNFa release, and IL10 expression. Methods: To investigate the role of Wnt pathway in the response of the enteric nervous system (ENS) to inflammation, neurons and glial cells from rat myenteric plexus were treated with exogenous Wnt3a and/or LPS with or without supporting neurotrophic factors such as basic fibroblast growth factor (bFGF), epithelial growth factor (EGF), and glial cell-derived neurotrophic factor (GDNF). The immunophenotypical characterization by flow cytometry and the protein and gene expression analysis by qPCR and Western blotting were carried out. Results: Flow cytometry and immunofluorescence staining evidenced that enteric neurons coexpressed Frizzled 9 and toll-like receptor 4 (TLR4) while glial cells were immunoreactive to TLR4 and Wnt3a suggesting that canonical Wnt signaling is active in ENS. Conclusions: The results of this study suggested the existence of neuronal surveillance through FZD9 and Wnt3a in enteric myenteric plexus. Moreover, experimental evidences were provided to clarify the correlation among soluble trophic factors, Wnt signaling, and anti-inflammatory protection of ENS
Vibration Damping Measurement on Car Windshields
Knowledge of the damping properties of a windshield is a fundamental element of the acoustical characterization of a car. The measuring method of damping for a windshield is presented in the paper. The damping loss factor – as a basic measure of mechanical damping – was determined experimentally by two means: the reverberation time from impact hammer testing as well as the modal behavior from 3D laser scanning vibrometer measurements. The results proved that the modal shapes have a fundamental effect on the measured damping values
Разработка и исследование возможностей кровати-трансформера для людей с ограниченными функциями
Магистерская диссертация посвящена разработке и исследованию медицинской кровати-трансформер. В процессе исследования физических возможностей человека, использующего и обслуживающего реабилитационную кровать, была спроектирована установка "Кровать-трансформер". В процессе создания установки было спроектировано несколько вариаций конструкции кровати с разным функционалом, а также в работе проведено исследование на сравнение приводов для трансформации кровати. В работе освещены такие темы как "Появление и трансформация с течением времени многофункциональных медицинских кроватей" и "Особенности больных с ограниченными возможностями". Проведены финансовые расчеты и исследования безопасности при производстве и эксплуатации конструкции.The master's thesis is devoted to the development and research of a medical transformer bed. In the process of studying the physical capabilities of a person using and servicing a rehabilitation bed, the “Transformer bed” installation was designed. In the process of creating the installation, several variations in the design of the bed with different functionalities were designed, and a study was conducted to compare the drives for transforming the bed. The work covers topics such as “The emergence and transformation over time of multifunctional medical beds” and “Features of patients with disabilities.” Conducted financial calculations and safety studies in the production and operation of the structure
Investigation of the evaporation process of liquefied hydrocarbons in front of a compressor
International audienceInlet fogging and wet compression are well known methods to lower the inlet temperature of air compressors of gas turbines and in this way lead to a more efficient compression process. Injection of water into the gas stream is another established method to reduce the compressor stage inlet temperature during the compression of crack gas. The lower inlet temperature of the compressor stage reduces its power demand and additionally, the discharge temperature remains in a suitable range. Applying the method of liquid injection, all injected droplets should be evaporated before entering the compressor impeller to avoid damage at the blades. A good knowledge about the evaporation process of injected liquid in a free stream is necessary to determine the required distance for complete evaporation of all droplets. The aim of this paper is to provide clear statements on technical possibilities and requirements for an optimized and reliable compression process under liquid injection. The evaporation process of injected hydrocarbon droplets into a gas stream is investigated under realistic boundary conditions. Using conservation laws of mass and energy, a 1D numerical model is derived which allows the calculation of the liquid hydrocarbon evaporation in a free stream. The required fluid properties are taken from the National Institute of Standards and Technology (NIST). A comparison between the 1D model and a 3D Navier-Stokes solution for injected CH 4 droplets into a CH 4 gas stream shows good agreement regarding the decrease of the droplet diameter during the evaporation with respect to the amount of injected mass of liquid fluid and gives a good indication of the requested distance for complete evaporation. In addition, the 1D model predicts the temperature decrease of the gas during evaporation in good accordance to a 3D Navier-Stokes solver. Applying the simple 1D model, it is possible to evaluate the thermodynamic inlet parameters of a compressor for given boundary conditions quickly. In addition, the results allow a statement regarding the complete evaporation of all sizes of injected droplets at the compressor inlet and the formation of liquid films at the walls
Gas Kinematics on GMC scales in M51 with PAWS: cloud stabilization through dynamical pressure
We use the high spatial and spectral resolution of the PAWS CO(1-0) survey of
the inner 9 kpc of the iconic spiral galaxy M51 to examine the effect of gas
streaming motions on the star-forming properties of individual GMCs. We compare
our view of gas flows in M51 -- which arise due to departures from axi-symmetry
in the gravitational potential (i.e. the nuclear bar and spiral arms) -- with
the global pattern of star formation as traced by Halpha and 24\mu m emission.
We find that the dynamical environment of GMCs strongly affects their ability
to form stars, in the sense that GMCs situated in regions with large streaming
motions can be stabilized, while similarly massive GMCs in regions without
streaming go on to efficiently form stars. We argue that this is the result of
reduced surface pressure felt by clouds embedded in an ambient medium
undergoing large streaming motions, which prevents collapse. Indeed, the
variation in gas depletion time expected based on the observed streaming
motions throughout the disk of M51 quantitatively agrees with the variation in
observed gas depletion time scale. The example of M51 shows that streaming
motions, triggered by gravitational instabilities in the form of bars and
spiral arms, can alter the star formation law; this can explain the variation
in gas depletion time among galaxies with different masses and morphologies. In
particular, we can explain the long gas depletion times in spiral galaxies
compared to dwarf galaxies and starbursts. We suggest that adding a dynamical
pressure term to the canonical free-fall time produces a single star formation
law that can be applied to all star-forming regions and galaxies, across cosmic
time.Comment: 28 pages, 14 figures, accepted for publication in Ap
The PdBI Arcsecond Whirlpool Survey (PAWS): Environmental Dependence of Giant Molecular Cloud Properties in M51
Using data from the PdBI Arcsecond Whirlpool Survey (PAWS), we have generated
the largest extragalactic Giant Molecular Cloud (GMC) catalog to date,
containing 1,507 individual objects. GMCs in the inner M51 disk account for
only 54% of the total 12CO(1-0) luminosity of the survey, but on average they
exhibit physical properties similar to Galactic GMCs. We do not find a strong
correlation between the GMC size and velocity dispersion, and a simple virial
analysis suggests that 30% of GMCs in M51 are unbound. We have analyzed the GMC
properties within seven dynamically-motivated galactic environments, finding
that GMCs in the spiral arms and in the central region are brighter and have
higher velocity dispersions than inter-arm clouds. Globally, the GMC mass
distribution does not follow a simple power law shape. Instead, we find that
the shape of the mass distribution varies with galactic environment: the
distribution is steeper in inter-arm region than in the spiral arms, and
exhibits a sharp truncation at high masses for the nuclear bar region. We
propose that the observed environmental variations in the GMC properties and
mass distributions are a consequence of the combined action of large-scale
dynamical processes and feedback from high mass star formation. We describe
some challenges of using existing GMC identification techniques for decomposing
the 12CO(1-0) emission in molecule-rich environments, such as M51's inner disk.Comment: 73 pages, 18 figures, 14 tables, accepted for publication in Ap
The PdBI Arcsecond Whirlpool Survey (PAWS): Multi-phase cold gas kinematic of M51
The kinematic complexity and the favorable position of M51 on the sky make
this galaxy an ideal target to test different theories of spiral arm dynamics.
Taking advantage of the new high resolution PdBI Arcsecond Whirlpool Survey
(PAWS) data, we undertake a detailed kinematic study of M51 to characterize and
quantify the origin and nature of the non-circular motions. Using a tilted-ring
analysis supported by several other archival datasets we update the estimation
of M51's position angle (PA=(173 +/- 3) deg) and inclination (i=(22 +/- 5)
deg). Harmonic decomposition of the high resolution (40 pc) CO velocity field
shows the first kinematic evidence of an m=3 wave in the inner disk of M51 with
a corotation at R(CR,m=3)=1.1 +/- 0.1 kpc and a pattern speed of Omega_p(m=3) =
140 km/(s kpc). This mode seems to be excited by the nuclear bar, while the
beat frequencies generated by the coupling between the m=3 mode and the main
spiral structure confirm its density-wave nature. We observe also a signature
of an m=1 mode that is likely responsible for the lopsidedness of M51 at small
and large radii. We provide a simple method to estimate the radial variation of
the amplitude of the spiral perturbation (Vsp) attributed to the different
modes. The main spiral arm structure has =50-70 km/s, while the streaming
velocity associated with the m=1 and m=3 modes is, in general, 2 times lower.
Our joint analysis of HI and CO velocity fields at low and high spatial
resolution reveals that the atomic and molecular gas phases respond differently
to the spiral perturbation due to their different vertical distribution and
emission morphology.Comment: 42 pages, 12 figures, accepted for publication in Ap
A Comparative Study of Giant Molecular Clouds in M51, M33 and the Large Magellanic Cloud
We compare the properties of giant molecular clouds (GMCs) in M51 identified
by the Plateau de Bure Interferometer Whirlpool Arcsecond Survey (PAWS) with
GMCs identified in wide-field, high resolution surveys of CO emission in M33
and the Large Magellanic Cloud (LMC). We find that GMCs in M51 are larger,
brighter and have higher velocity dispersions relative to their size than
equivalent structures in M33 and the LMC. These differences imply that there
are genuine variations in the average mass surface density of the different GMC
populations. To explain this, we propose that the pressure in the interstellar
medium surrounding the GMCs plays a role in regulating their density and
velocity dispersion. We find no evidence for a correlation between size and
linewidth in any of M51, M33 or the LMC when the CO emission is decomposed into
GMCs, although moderately robust correlations are apparent when regions of
contiguous CO emission (with no size limitation) are used. Our work
demonstrates that observational bias remains an important obstacle to the
identification and study of extragalactic GMC populations using CO emission,
especially in molecule-rich galactic environments.Comment: 25 pages, 11 figures, accepted for publication in ApJ. Uses
emulateapj LaTeX macros. For more information on PAWS, further papers and
data, see http://www.mpia.de/PAWS
Copious Amounts of Dust and Gas in a z=7.5 Quasar Host Galaxy
We present IRAM/NOEMA and JVLA observations of the quasar J1342+0928 at
z=7.54 and report detections of copious amounts of dust and [CII] emission in
the interstellar medium (ISM) of its host galaxy. At this redshift, the age of
the universe is 690 Myr, about 10% younger than the redshift of the previous
quasar record holder. Yet, the ISM of this new quasar host galaxy is
significantly enriched by metals, as evidenced by the detection of the [CII]
158micron cooling line and the underlying far-infrared (FIR) dust continuum
emission. To the first order, the FIR properties of this quasar host are
similar to those found at a slightly lower redshift (z~6), making this source
by far the FIR-brightest galaxy known at z>7.5. The [CII] emission is spatially
unresolved, with an upper limit on the diameter of 7 kpc. Together with the
measured FWHM of the [CII] line, this yields a dynamical mass of the host of
<1.5x10^11 M_sun. Using standard assumptions about the dust temperature and
emissivity, the NOEMA measurements give a dust mass of (0.6-4.3)x10^8 M_sun.
The brightness of the [CII] luminosity, together with the high dust mass, imply
active ongoing star formation in the quasar host. Using [CII]-SFR scaling
relations, we derive star formation rates of 85-545 M_sun/yr in the host,
consistent with the values derived from the dust continuum. Indeed, an episode
of such past high star formation is needed to explain the presence of ~10^8
M_sun of dust implied by the observations.Comment: 8 pages, 4 figures. Published in ApJ Letter
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The High-Density Ionized Gas in the Central Parsec of the Galaxy
We report a study of the line emission at 1.3 mm from the region around Sgr A* made with the Submillimeter Array at a resolution of 2'' over a field of 60'' (2 pc) and a velocity range of . This field encompasses most of the Galactic center's "minispiral." With an isothermal homogeneous H II model, we determined the physical conditions of the ionized gas at specific locations in the Northern and Eastern Arms from the line data along with Very Large Array data from the line at 3.6 cm and from the radio continuum emission at 1.3 cm. The typical electron density and kinetic temperature in the minispiral arms are and 5000-13,000 K, respectively. The and line profiles are broadened due to the large velocity shear within and along the beam produced by dynamical motions in the strong gravitational field near Sgr A*. We constructed a three-dimensional model of the minispiral using the orbital parameters derived under the assumptions that the gas flows are in Keplerian motion. The gas in the Eastern Arm appears to collide with the Northern Arm flow in the "Bar" region, which is located 0.1-0.2 pc south of and behind Sgr A*. Finally, a total Lyman continuum flux of photons is inferred from the assumption that the gas is photoionized and the ionizing photons for the high-density gas in the minispiral arms are from external sources, which is equivalent to ~250 O9-type zero-age-main-sequence stars.Astronom
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