3,380 research outputs found
Masers and the Massive Star Formation Process: New Insights Through Infrared Observations
Our mid-infrared and near-infrared surveys over the last five years have
helped to strengthen and clarify the relationships between water, methanol, and
OH masers and the star formation process. Our surveys show that maser emission
seems to be more closely associated with mid-infrared emission than cm radio
continuum emission from UC HII regions. We find that masers of all molecular
species surveyed trace a wide variety of phenomena and show a proclivity for
linear distributions. The vast majority of these linear distributions can be
explained by outflows or shocks, and in general do not appear to trace
circumstellar disks as was previously thought. Some water and methanol masers
that are not associated with radio continuum emission appear to trace
infrared-bright hot cores, the earliest observable stage of massive stellar
life before the onset of a UC HII region.Comment: 6 pages, 3 figures, to appear in the proceedings of IAU Symposium
227: "Massive Star Birth: A Crossroads of Astrophysics", version with
full-resolution images available at http://www.ctio.noao.edu/~debuize
Microbial and chemical changes during the spontaneous ensilage of grape pomace
Pilot scale fermentations with grape pomace from two different wineries were investigated during the 24 weeks of the ensiling period, along with laboratory scale experiments in which the environmental temperatures were held constant at 20, 25, 30 and 35 °C. During this period, yeast and lactic acid bacteria (LAB) counts were made, after which the identity of both groups of organisms was studied, as were the major microbial metabolites present. Major microbial and chemical alterations occurred during the first 3 weeks of ensilage, leaving a more stable product differing significantly from the initial substrate. The results obtained indicated that after initial growth, yeast and LAB populations undergo progressive inactivation at environmental temperatures above 20 °C, although LAB seem to adjust better to this specific, post-fermentation environment. Homofermentative species of Lactobacillus were the dominant LAB. The initial yeast flora of non-Saccharomyces species was replaced by a typical wine yeast flora, i.e. predominantly Saccharomyces cerevisiae. At the chemical level, major alterations were due to an alcoholic fermentation and a malolactic conversion within the first 3 weeks
Mapping quantitative trait Loci associated with graft (In)compatibility in apricot (Prunus armeniaca L.)
Graft incompatibility (GI) between the most popular Prunus rootstocks and apricot cultivars is one of the major problems for rootstock usage and improvement. Failure in producing long-leaving healthy grafts greatly affects the range of available Prunus rootstocks for apricot cultivation. Despite recent advances related to the molecular mechanisms of a graft-union formation between rootstock and scion, information on genetic control of this trait in woody plants is essentially missing because of a lack of hybrid crosses, segregating for the trait. In this study, we have employed the next-generation sequencing technology to generate the single-nucleotide polymorphism (SNP) markers and construct parental linkage maps for an apricot F1 population “Moniqui (Mo)” × “Paviot (Pa)” segregating for ability to form successful grafts with universal Prunus rootstock “Marianna 2624”. To localize genomic regions associated with this trait, we genotyped 138 individuals from the “Mo × Pa” cross and constructed medium-saturated genetic maps. The female “Mo” and male “Pa” maps were composed of 557 and 501 SNPs and organized in eight linkage groups that covered 780.2 and 690.4 cM of genetic distance, respectively. Parental maps were aligned to the Prunus persica v2.0 genome and revealed a high colinearity with the Prunus reference map. Two-year phenotypic data for characters associated with unsuccessful grafting such as necrotic line (NL), bark and wood discontinuities (BD and WD), and an overall estimate of graft (in)compatibility (GI) were collected for mapping quantitative trait loci (QTLs) on both parental maps. On the map of the graft-compatible parent “Pa”, two genomic regions on LG5 (44.9–60.8 cM) and LG8 (33.2–39.2 cM) were associated with graft (in)compatibility characters at different significance level, depending on phenotypic dataset. Of these, the LG8 QTL interval was most consistent between the years and supported by two significant and two putative QTLs. To our best knowledge, this is the first report on QTLs for graft (in)compatibility in woody plants. Results of this work will provide a valuable genomic resource for apricot breeding programs and facilitate future efforts focused on candidate genes discovery for graft (in)compatibility in apricot and other Prunus species
High-Resolution Mid-Infrared Morphology of Cygnus A
We present subarcsecond resolution mid-infrared images at 10.8 and 18.2
microns of Cygnus A. These images were obtained with the University of Florida
mid-IR camera/spectrometer OSCIR at the Keck II 10-m telescope. Our data show
extended mid-IR emission primarily to the east of the nucleus with a possible
western extension detected after image deconvolution. This extended emission is
closely aligned with the bi-conical structure observed at optical and near-IR
wavelengths by the HST. This emission is consistent with dust heated from the
central engine of Cygnus A. We also marginally detect large-scale low level
emission extending > 1.5 kpc from the nucleus which may be caused by in-situ
star formation, line emission, and/or PAH contamination within the bandpass of
our wide N-band filter.Comment: 20 pages, 8 figures, accepted for publication in the Astrophysical
Journa
Metrics with Prescribed Ricci Curvature near the Boundary of a Manifold
Suppose is a manifold with boundary. Choose a point . We
investigate the prescribed Ricci curvature equation \Ric(G)=T in a
neighborhood of under natural boundary conditions. The unknown here is
a Riemannian metric. The letter in the right-hand side denotes a
(0,2)-tensor. Our main theorems address the questions of the existence and the
uniqueness of solutions. We explain, among other things, how these theorems may
be used to study rotationally symmetric metrics near the boundary of a solid
torus . The paper concludes with a brief discussion of the Einstein
equation on .Comment: 13 page
Mid-Infrared Imaging of NGC 6334 I
We present high-resolution (<0.5") mid-infrared Keck II images of individual
sources in the central region of NGC 6334 I. We compare these images to images
at a variety of other wavelengths from the near infrared to cm radio continuum
and speculate on the nature of the NGC 6334 I sources. We assert that the
cometary shape of the UCHII region here, NGC 6334 F, is due to a champagne-like
flow from a source on the edge of a molecular clump and not a due to a bow
shock caused by the supersonic motion of the UCHII region through the
interstellar medium. The mid-infrared emission in concentrated into an arc of
dust that define the boundary between the UCHII region and the molecular clump.
This dust arc contains a majority of the masers in the region. We discuss the
nature of the four near-infrared sources associated with IRS-I 1, and suggest
that one of the sources, IRS1E, is responsible for the heating and ionizing of
the UCHII region and the mid-infrared dust arc. Infrared source IRS-I 2, which
has been thought to be a circumstellar disk associated with a linear
distribution of methanol masers, is found not to be directly coincident with
the masers and elongated at a much different position angle. IRS-I 3 is found
to be a extended source of mid-infrared emission coming from a cluster of young
dusty sources seen in the near-infrared.Comment: Accepted for publication by the Astrophysical Journal, 27 pages, 9
figure
Effect of Polymer Hydration on the Kinetic Release of Drugs: A Study of Ibuprofen and Ketoprofen in HPMC Matrices
Samples of drug/hydroxypropylmethylcellulose (HPMC) mixtures and matrices (drug/HPMC mixtures plus excipients) were allowed to equilibrate in closed chambers with defined relative humidities (RHs). Their water uptake and drug release were evaluated by differential scanning calorimetry/thermogravimetric analysis and dissolution studies, respectively. Analysis of the thermal behaviors of the drug/HPMC mixtures and of the polymer alone, as functions of RH, leads to the conclusion that most of the hydration water is retained by the polymer, and points to the occurrence of different types of hydration water, from the strongly polymer-bound water molecules at RH values up to 81%, to the almost “free water” for RH values close to 100%. In addition, application of the Korsmeyer model to the dissolution results leads to the conclusion that the rate determining dissolution processes are predominantly of the fickian type.http://www.informaworld.com/10.1081/DDC-12001820
Avulsión del tubérculo tibial asociada a epifisiólisis proximal de tibia
Las lesiones de la tuberosidad tibial anterior son fracturas poco frecuentes que se
presentan generalmente en adolescentes. Su extensión fisaria hacia la cortical posterior constituye
un hecho infrecuente. Algunos autores consideran necesaria la modificación de la clasifícacion
de Watson-Jones añadiéndole un tipo IV. Se presenta un caso de epifisiólisis proximal de tibia asociada
a avulsión del tubérculo tibial, se discute dicha clasificación, el mecanismo de producción
y revisión de la literaturaFractures of the anterior tibial tubercle are uncommon lesions, adolescents being
more frequently affected. Physeal extension through the posterior tibial cortical bone is rare. Some
authors have suggested that a new type IV can be added to the Watson-Jones classiflcation. In
this paper, we report a case with epiphysiolisis of the proximal tibia associated to an avulsion fracture
of the anterior tibial tubercle. The Watson-Jones classiflcation, the mechanism of injury are
discussed together a review of the literature
Analysis of linezolid and tigecycline as candidates for local prophylaxis via antibiotic-loaded bone cement
Objectives To assess the Gram-positive-specific antibiotic linezolid and the broad-spectrum antibiotic tigecycline for use in local antibiotic delivery via antibiotic-loaded bone cement.
Methods Linezolid and tigecycline were added to Biomet bone cement at varying concentrations. Antibiotic elution over 1 week was quantified by HPLC-MS. The effect of wear on elution over 51 h was determined using a modified TE-66 wear tester. Eluted antibiotics were used to determine the MICs for a panel of clinically relevant bacteria. The impact strength of antibiotic-loaded samples was determined using a Charpy-type impact testing apparatus. Cytotoxicity of eluted antibiotics against MG-63 cells was evaluated using an MTT assay.
Results Linezolid and tigecycline eluted from bone cement to clinically relevant levels within 1 h and retained activity over 1 week. Mechanical wear significantly reduced elution of tigecycline, but had little effect on elution of linezolid. Linezolid showed low cytotoxicity towards MG-63 cells with ≤300 mg/mL resulting in >50% cell activity. Cytotoxicity of tigecycline was higher, with an IC50 of 5–10 mg/L.
Conclusions Linezolid and tigecycline retain activity after elution from bone cement. The concentration of tigecycline may need to be carefully controlled due to cytotoxicity. The effect of wear on bone cement may need to be considered if tigecycline is to be used for local delivery. Up to 10% linezolid can be added without affecting the impact strength of the bone cement. These results are promising indications for future investigation of these antibiotics for use in local antibiotic delivery strategies
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