1,404 research outputs found
Microstructure of melt-processed Bi2Sr2CaCu2Oy and reaction mechanisms during post heat treatment
Phase compositions and microstructures of melt processed 2212 were studied. 2212 starting powder was cooled from temperatures between 910 °C and 1100 °C in air at rates ranging from 350 K/min to 0.083 K/min. The solidification sequence was established for all cooling rates. Under all conditions the Bi-free (Sr, Ca)CuO2 (01x1) is the primary phase. The one-layer solid solution 11905 nucleates on this phase. The residual liquid solidifies to a glassy state, decomposes into the eutectic of Cu2O and Bi2Sr2.1Ca0.9Ox, or reacts with the primary phase and the 11905 forming 2212 at high, intermediate, or low cooling rates, respectively. Post solidification heat treatment at 850 °C in air leads to partial remelting. The Cu-rich liquid reacts with 11905 and 01x1 forming 2212. Subsequent solid/solid reactions lead to a high volume fraction of 2212 with almost ideal 2 : 2 : 1 : 2 stoichiometr
Owner reported clinical signs and -treatment decisions in equine pastern dermatitis.
INTRODUCTION
Equine pastern dermatitis has a high prevalence in the equine population, especially in draft breeds. This skin condition is difficult to treat, and it is suspected that owners often decide on a treatment without consulting a veterinarian. The objectives of this study were to describe owner-reported clinical signs, severity, and reasons to consult a veterinarian. Moreover, we inquired about preventive measures and treatments, both instituted by owners without previous consultation or prescribed by their veterinarians. A total of 123 horses (owners recruited over social media) were included in the study. All horses suffered from equine pastern dermatitis at least once in the two years preceding the study. Standardized questionnaires collecting information on management, housing conditions, clinical signs as well as preventive measures and treatments were filled out by participants. The data was recorded, and descriptive statistics were performed. Most horses (71 out of 115 available answers, 62 %) had shown clinical signs of equine pastern dermatitis at least four times in their lives. A total of 113 horses (92 % of all included horses) were affected by equine pastern dermatitis at the time of the interview. For 37 horses (32 %) out of 114 available answers the owners consulted their veterinarian only after the horse showed signs of pain or lameness. Usually, treatments that did not require a medical prescription were applied without consulting their veterinarian (e. g. only 9 % (14 out of 150 prescriptions) of topical creams promoting wound healing were prescribed by a veterinarian). A total of 31 treatment decisions (55 %) with creams containing anti-bacterial, anti-mycotic and/or anti-inflammatory agents and 100 % of systemic medications containing anti-bacterial, anti-parasitic or anti-inflammatory agents were prescribed by veterinarians. Overall, 69 % of treatment decisions were made without consulting a veterinarian, making it then more difficult to determine underlying causes for the pastern dermatitis and rendering the treatment often longer and more onerous. To raise owner awareness of possible consequences if a veterinarian is consulted too late in the disease process, specific information campaigns to improve animal welfare should be considered
The GREATS H+[OIII] Luminosity Function and Galaxy Properties at : Walking the Way of JWST
The James Webb Space Telescope will allow to spectroscopically study an
unprecedented number of galaxies deep into the reionization era, notably by
detecting [OIII] and H nebular emission lines. To efficiently prepare
such observations, we photometrically select a large sample of galaxies at
and study their rest-frame optical emission lines. Combining data from
the GOODS Re-ionization Era wide-Area Treasury from Spitzer (GREATS) survey and
from HST, we perform spectral energy distribution (SED) fitting, using
synthetic SEDs from a large grid of photoionization models. The deep
Spitzer/IRAC data combined with our models exploring a large parameter space
enables to constrain the [OIII]+H fluxes and equivalent widths for our
sample, as well as the average physical properties of galaxies, such
as the ionizing photon production efficiency with
. We
find a relatively tight correlation between the [OIII]+H and UV
luminosity, which we use to derive for the first time the [OIII]+H
luminosity function (LF) at . The [OIII]+H LF is higher
at all luminosities compared to lower redshift, as opposed to the UV LF, due to
an increase of the [OIII]+H luminosity at a given UV luminosity from
to . Finally, using the [OIII]+H LF, we make
predictions for JWST/NIRSpec number counts of galaxies. We find that
the current wide-area extragalactic legacy fields are too shallow to use JWST
at maximal efficiency for spectroscopy even at 1hr depth and JWST
pre-imaging to mag will be required.Comment: 13 pages, 9 figures, accepted for publication in MNRA
Spectroscopic Constraints on UV Metal Line Emission at z~6-9: The Nature of Lyman-alpha Emitting Galaxies in the Reionization-Era
Recent studies have revealed intense UV metal emission lines in a modest
sample of z>7 Lyman-alpha emitters, indicating a hard ionizing spectrum is
present. If such high ionization features are shown to be common, it may
indicate that extreme radiation fields play a role in regulating the visibility
of Lyman-alpha in the reionization era. Here we present deep near-infrared
spectra of seven galaxies with Lyman-alpha emission at 5.4<z<8.7 (including a
newly-confirmed lensed galaxy at z=6.031) and three bright z>7 photometric
targets. In nine sources we do not detect UV metal lines. However in the
z=8.683 galaxy EGSY8p7, we detect a 4.6 sigma emission line in the narrow
spectral window expected for NV 1243. The feature is unresolved (FWHM<90 km/s)
and is likely nebular in origin. A deep H-band spectrum of EGSY8p7 reveals
non-detections of CIV, He II, and OIII]. The presence of NV requires a
substantial flux of photons above 77 eV, pointing to a hard ionizing spectrum
powered by an AGN or fast radiative shocks. Regardless of its origin, the
intense radiation field of EGSY8p7 may aid the transmission of Lyman-alpha
through what is likely a partially neutral IGM. With this new detection, five
of thirteen known Lyman-alpha emitters at z>7 have now been shown to have
intense UV line emission, suggesting that extreme radiation fields are
commonplace among the Lyman-alpha population. Future observations with JWST
will eventually clarify the origin of these features and explain their role in
the visibility of Lyman-alpha in the reionization era.Comment: 15 pages, 3 tables and 7 figures. Accepted for publication in MNRA
A spectroscopically confirmed z=1.327 galaxy-scale deflector magnifying a z~8 Lyman-Break galaxy in the Brightest of Reionizing Galaxies survey
We present a detailed analysis of an individual case of gravitational lensing
of a Lyman-Break galaxy (LBG) in a blank field, identified in Hubble
Space Telescope imaging obtained as part of the Brightest of Reionizing
Galaxies survey. To investigate the close proximity of the bright
() -dropout to a small group of foreground galaxies, we
obtained deep spectroscopy of the dropout and two foreground galaxies using
VLT/X-Shooter. We detect H-, H-, [OIII] and [OII] emission in
the brightest two foreground galaxies (unresolved at the natural seeing of
arcsec), placing the pair at . We can rule out emission lines
contributing all of the observed broadband flux in band at
, allowing us to exclude the candidate as a low redshift
interloper with broadband photometry dominated by strong emission lines. The
foreground galaxy pair lies at the peak of the luminosity, redshift and
separation distributions for deflectors of strongly lensed objects,
and we make a marginal detection of a demagnified secondary image in the
deepest () filter. We show that the configuration can be accurately
modelled by a singular isothermal ellipsoidal deflector and a S\'{e}rsic source
magnified by a factor of . The reconstructed source in the
best-fitting model is consistent with luminosities and morphologies of
LBGs in the literature. The lens model yields a group mass of
and a stellar mass-to-light ratio for the
brightest deflector galaxy of within its effective radius. The foreground galaxies'
redshifts would make this one of the few strong lensing deflectors discovered
at .Comment: Accepted for publication in MNRAS. 16 pages, 11 figures, 3 table
First Frontier Field Constraints on the Cosmic Star-Formation Rate Density at z~10 - The Impact of Lensing Shear on Completeness of High-Redshift Galaxy Samples
We search the complete Hubble Frontier Field dataset of Abell 2744 and its
parallel field for z~10 sources to further refine the evolution of the cosmic
star-formation rate density (SFRD) at z>8. We independently confirm two images
of the recently discovered triply-imaged z~9.8 source by Zitrin et al. (2014)
and set an upper limit for similar z~10 galaxies with red colors of
J_125-H_160>1.2 in the parallel field of Abell 2744. We utilize extensive
simulations to derive the effective selection volume of Lyman-break galaxies at
z~10, both in the lensed cluster field and in the adjacent parallel field.
Particular care is taken to include position-dependent lensing shear to
accurately account for the expected sizes and morphologies of highly-magnified
sources. We show that both source blending and shear reduce the completeness at
a given observed magnitude in the cluster, particularly near the critical
curves. These effects have a significant, but largely overlooked, impact on the
detectability of high-redshift sources behind clusters, and substantially
reduce the expected number of highly-magnified sources. The detections and
limits from both pointings result in a SFRD which is higher by 0.4+-0.4 dex
than previous estimates at z~10 from blank fields. Nevertheless, the
combination of these new results with all other estimates remain consistent
with a rapidly declining SFRD in the 170 Myr from z~8 to z~10 as predicted by
cosmological simulations and dark-matter halo evolution in LambdaCDM. Once
biases introduced by magnification-dependent completeness are accounted for,
the full six cluster and parallel Frontier Field program will be an extremely
powerful new dataset to probe the evolution of the galaxy population at z>8
before the advent of the JWST.Comment: 10 pages, 7 figures, changed to match accepted version to appear in
Ap
High-precision Photometric Redshifts from Spitzer/IRAC: Extreme [3.6]-[4.5] Colors Identify Galaxies in the Redshift Range z~6.6-6.9
One of the most challenging aspects of studying galaxies in the z>~7 universe
is the infrequent confirmation of their redshifts through spectroscopy, a
phenomenon thought to occur from the increasing opacity of the intergalactic
medium to Lya photons at z>6.5. The resulting redshift uncertainties inhibit
the efficient search for [C II] in z~7 galaxies with sub-mm instruments such as
ALMA, given their limited scan speed for faint lines. One means by which to
improve the precision of the inferred redshifts is to exploit the potential
impact of strong nebular emission lines on the colors of z~4-8 galaxies as
observed by Spitzer/IRAC. At z~6.8, galaxies exhibit IRAC colors as blue as
[3.6]-[4.5] ~-1, likely due to the contribution of [O III]+Hb to the 3.6 mum
flux combined with the absence of line contamination in the 4.5 mum band. In
this paper we explore the use of extremely blue [3.6]-[4.5] colors to identify
galaxies in the narrow redshift window z~6.6-6.9. When combined with an
I-dropout criterion, we demonstrate that we can plausibly select a relatively
clean sample of z~6.8 galaxies. Through a systematic application of this
selection technique to our catalogs from all five CANDELS fields, we identify
20 probable z~6.6-6.9 galaxies. We estimate that our criteria select the ~50%
strongest line emitters at z~6.8 and from the IRAC colors we estimate a typical
[O III]+Hb rest-frame equivalent width of 1085A for this sample. The small
redshift uncertainties on our sample make it particularly well suited for
follow-up studies with facilities such as ALMA.Comment: In submission to the Astrophysical Journal, updated in response to
the referee report, 13 pages, 11 figures, 1 tabl
The Impact of Strong Gravitational Lensing on Observed Lyman-Break Galaxy Numbers at 4<z<8 in the GOODS and the XDF Blank Fields
Detection of Lyman-Break Galaxies (LBGs) at high-redshift can be affected by
gravitational lensing induced by foreground deflectors not only in galaxy
clusters, but also in blank fields. We quantify the impact of strong
magnification in the samples of , , , LBGs () observed in the XDF and GOODS/CANDELS fields, by investigating the
proximity of dropouts to foreground objects. We find that of bright
LBGs () by
foreground objects. This fraction decreases from at to
at . Since the observed fraction of strongly lensed
galaxies is a function of the shape of the luminosity function (LF), it can be
used to derive Schechter parameters, and , independently
from galaxy number counts. Our magnification bias analysis yields
Schechter-function parameters in close agreement with those determined from
galaxy counts albeit with larger uncertainties. Extrapolation of our analysis
to suggests that future surveys with JSWT, WFIRST and EUCLID
should find excess LBGs at the bright-end, even if there is an intrinsic
exponential cutoff of number counts. Finally, we highlight how the
magnification bias measurement near the detection limit can be used as probe of
the population of galaxies too faint to be detected. Preliminary results using
this novel idea suggest that the magnification bias at is not
as strong as expected if extends well below the current
detection limits in the XDF. At face value this implies a flattening of the LF
at . However, selection effects and completeness estimates
are difficult to quantify precisely. Thus, we do not rule out a steep LF
extending to .Comment: Submitted to ApJ on 18/12/201
Lyman-alpha Emission from a Luminous z=8.68 Galaxy: Implications for Galaxies as Tracers of Cosmic Reionization
We report the discovery of Lyman-alpha emission (Ly) in the bright
galaxy EGSY-2008532660 (hereafter EGSY8p7) using the MOSFIRE spectrograph at
the Keck Observatory. First reported by Roberts-Borsani et al. (2015), it was
selected for spectroscopic observations because of its photometric redshift
(), apparent brightness (H)
and red Spitzer/IRAC [3.6]-[4.5] color indicative of contamination by strong
oxygen emission in the [4.5] band. With a total integration of 4.3 hours,
our data reveal an emission line at 11776 {\AA} which we argue is
likely Ly at a redshift , in good
agreement with the photometric estimate. The line was detected independently on
two nights using different slit orientations and its detection significance is
. An overlapping skyline contributes significantly to the
uncertainty on the total line flux although the significance of the detected
line is robust to a variety of skyline-masking procedures. By direct addition
and a Gaussian fit, we estimate a 95\% confidence range of
1.0--2.5 erg s cm, corresponding to a rest-frame
equivalent width of 17--42 {\AA}. EGSY8p7 is the most distant galaxy confirmed
spectroscopically to date, and the third luminous source in the EGS field
beyond with detectable Ly emission viewed at a
time when the intergalactic medium is believed to be fairly neutral. Although
the reionization process was probably patchy, we discuss whether luminous
sources with prominent IRAC color excesses may harbor harder ionizing spectra
than the dominant fainter population thereby creating earlier ionized bubbles.
Further spectroscopic follow-up of such bright sources promises important
insight into the early formation of galaxies.Comment: V3: ApJL accepted; 7 pages, 4 figures, 1 tabl
Alar Rim Grafts
Alar rim grafts date back to the 1950s for the correction of alar base in cleft lip nose. Cartilage struts under the anterior half of the alae of a pinched nose tip were popularised and the cartilage of the auricular concha became the donor site of choice for nasal procedures. Recently, some surgeons pointed to its potential role in aesthetic cases and added some technical refinements. These grafts are used for open and closed rhinoplasties. They usually consist of a rod of septal or auricular cartilage that we lay as reinforcement inside a pocket along the alar margin. Indications include the following: congenital or traumatic asymmetry, dynamic alar collapse, alar flare, primary retraction or notching, secondary (surgical or traumatic) retraction and malposition of the lateral cartilages (upwards or downwards). Harvesting and implanting techniques as well as the possible drawbacks are discussed
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