1,088 research outputs found
The effects of a retinoblastoma derived growth factor on the healing of experimental wounds in the rabbit lens and retina
Water vapor emission from IRC+10216 and other carbon-rich stars: model predictions and prospects for multitransition observations
We have modeled the emission of H2O rotational lines from the extreme C-rich
star IRC+10216. Our treatment of the excitation of H2O emissions takes into
account the excitation of H2O both through collisions, and through the pumping
of the nu2 and nu3 vibrational states by dust emission and subsequent decay to
the ground state. Regardless of the spatial distribution of the water
molecules, the H2O 1_{10}-1_{01} line at 557 GHz observed by the Submillimeter
Wave Astronomy Satellite (SWAS) is found to be pumped primarily through the
absorption of dust-emitted photons at 6 m in the nu2 band. As noted by
previous authors, the inclusion of radiative pumping lowers the ortho-H2O
abundance required to account for the 557 GHz emission, which is found to be
(0.5-1)x10^{-7} if the presence of H2O is a consequence of vaporization of
orbiting comets or Fischer-Tropsch catalysis. Predictions for other
submillimeter H2O lines that can be observed by the Herschel Space Observatory
(HSO) are reported. Multitransition HSO observations promise to reveal the
spatial distribution of the circumstellar water vapor, discriminating among the
several hypotheses that have been proposed for the origin of the H2O vapor in
the envelope of IRC+10216. We also show that, for observations with HSO, the
H2O 1_{10}-1_{01} 557 GHz line affords the greatest sensitivity in searching
for H2O in other C-rich AGB stars.Comment: 35 pages, 12 figures, to be published in The Astrophysical Journa
Delayed-onset endophthalmitis associated with corneal suture infections
BACKGROUND: The purpose of the current study was to report the microbiology, risk factors, and treatment outcomes in patients with delayed-onset endophthalmitis associated with corneal suture infections. For this retrospective consecutive case series, a search of the ocular microbiology department database was performed to identify all patients with positive corneal and intraocular cultures (anterior chamber and/or vitreous) between 01 January 1995 and 01 January 2010. A subset of patients with a history of corneal suture infections and delayed-onset endophthalmitis was identified. RESULTS: Over the 15-year period of the study, 68 patients were identified to have both positive corneal and intraocular cultures. Among them, six patients were identified to have a culture-proven, delayed-onset endophthalmitis that developed from a culture-positive corneal suture infection. All of the patients in the current study were using topical corticosteroids at the time of diagnosis. In four of six patients, there was documented manipulation of a suture before the development of endophthalmitis. Streptoccocus was identified as the causative organism in five of six patients in the current study. All of the Streptoccocus isolates were sensitive to vancomycin. The single case of Serratia marcescens endophthalmitis was sensitive to amikacin, ceftazidime, ciprofloxacin, gentamicin, and tobramycin. Treatment modalities varied and were guided by the attending ophthalmologist depending upon clinical presentation. One patient with severe Streptococcus pyogenes keratitis and endophthalmitis underwent a primary enucleation after developing a wound dehiscence. Of the remaining five patients, all received topical and intravitreal antibiotics. Therapeutic penetrating keratoplasty was performed in three patients. Pars plana vitrectomy was performed in two patients. Visual acuity outcomes ranged from 20/150 to no light perception. CONCLUSIONS: In the current study, Streptococcus was isolated in nearly all patients with delayed-onset endophthalmitis associated with corneal suture infections. Topical steroid use and suture manipulation were identified as associated factors for developing endophthalmitis. Visual acuity outcomes were poor despite the prompt recognition of endophthalmitis and appropriate antibiotic therapy
High-excitation OH and H_2O lines in Markarian 231: the molecular signatures of compact far-infrared continuum sources
The ISO/LWS far-infrared spectrum of the ultraluminous galaxy Mkn 231 shows
OH and H_2O lines in absorption from energy levels up to 300 K above the ground
state, and emission in the [O I] 63 micron and [C II] 158 micron lines. Our
analysis shows that OH and H_2O are radiatively pumped by the far-infrared
continuum emission of the galaxy. The absorptions in the high-excitation lines
require high far-infrared radiation densities, allowing us to constrain the
properties of the underlying continuum source. The bulk of the far-infrared
continuum arises from a warm (T_dust=70-100 K), optically thick
(tau_100micron=1-2) medium of effective diameter 200-400 pc. In our best-fit
model of total luminosity L_IR, the observed OH and H2O high-lying lines arise
from a luminous (L/L_IR~0.56) region with radius ~100 pc. The high surface
brightness of this component suggests that its infrared emission is dominated
by the AGN. The derived column densities N(OH)>~10^{17} cm^{-2} and
N(H_2O)>~6x10^{16} cm^{-2} may indicate XDR chemistry, although significant
starburst chemistry cannot be ruled out. The lower-lying OH, [C II] 158 micron,
and [O I] 63 micron lines arise from a more extended (~350 pc) starburst
region. We show that the [C II] deficit in Mkn 231 is compatible with a high
average abundance of C+ because of an extreme overall luminosity to gas mass
ratio. Therefore, a [C II] deficit may indicate a significant contribution to
the luminosity by an AGN, and/or by extremely efficient star formation.Comment: 16 pages, 6 figures, accepted for publication in The Astrophysical
Journa
METAS ACADÉMICAS, ESTRATEGIAS Y AUTOEFICACIA: UN ANÁLISIS DIFERENCIAL ENTRE EL RENDIMIENTO ACADÉMICO ALTO Y BAJO DEL ALUMNADO DE EDUCACIÓN SECUNDARIA
En este artículo se trata de conocer, primeramente, las correlaciones existentes entre las metas académicas y las estrategias de aprendizaje, autoeficacia y el rendimiento académico del alumnado de Educación secundaria de Galicia (España) y del Norte de Portugal. Además el objetivo está en lograr el conocimiento de posibles diferencias significativas existentes de cada una de las variables y el rendimiento alto y bajo del alumnado. La muestra incluye 997 alumnos de 7º curso de Enseñanza Básica (Portugal) y de primer curso de Educación Secundaria (España) y 510 son del norte de Portugal (48% varones), de edades comprendidas entre 10 y 16 años, (M=12,4 años y DT = 0,94 años) y 487 son alumnos de Galicia (España) (51% varones), de edades entre 11 y 15 años, (M= 12,3 años y DT = 0,70). Los resultados señalan que son la Autoeficacia/autorregulación y estrategias de apoyo, las Metas de aprendizaje, las de Rendimiento/logro y las Estrategias de organización y comprensión las que mantienen una correlación positiva y significativa con el Rendimiento académico en la muestra de Portugal. En la muestra de Galicia se dan las mismas correlaciones, con la salvedad de que las Metas de aprendizaje, aunque con correlación positiva, no resultan significativas. Sin embargo las variables de Metas de valoración social, Metas de evitación de fracaso y Ansiedad ante exámenes guardan correlaciones negativas con el rendimiento académico. En cuanto a las diferencias significativas de las mismas variables en relación con el rendimiento alto y bajo se ha comprobado, en ambas muestras, que las variables Metas de rendimiento/logro, Metas de aprendizaje, Autoeficacia/autorregulación, Estrategias de organización y comprensión presentan diferencias estadísticamente significativas, lo que significa que en los alumnos de rendimiento alto muestran valores superiores frente a los alumnos de rendimiento bajo. Sin embargo, las variables Metas de evitación de fracaso, Metas de valoración social y Metas de ansiedad ante exámenes muestran valores más elevados los alumnos de rendimiento bajo frente a los de rendimiento alto. Con estos resultados se proponen algunas pautas de mejora del rendimiento para alumnos con dificultades en aprendizaje.
Palabras clave: autoeficacia, estrategias de aprendizaje, metas de rendimiento, metas acadêmicas de aprendizaje, rendimiento acadêmic
A 800 kW wind-diesel test bench based on the MADE AE-52 variable speed wind turbine
A field work have been made about the practical installation of a wind-diesel autonomous power system. A remarkable innovation on the control of the latter wind-diesel system is the ability of taking advantage of the kinetic energy available from the wind turbine. With such an extra energy, a power quality improvement can be achieved in the presence of load commutations. Besides of that, a convenient power sharing out can be obtained, allowing a high renewable energy penetration and fuel savings. Several results show the behaviour of the whole system, apart of the power quality improvement. Index Terms—Renewable hybrid system, isolated power system, power quality, diesel generator, wind turbine
Induction of organogenesis in vitro with 6-benzylaminopurine in Cattleya trianae Linden & Rchb.f.
La orquídea Cattleya trianae Linden & Rchb.f. es reconocida como flor nacional de Colombia y se encuentra en peligro crítico, al presentar una reducción estimada mayor al 80% en los últimos 100 años, debido a la disminución en la calidad del hábitat y niveles altos de explotación o recolección. La familia Orchidaceae es una de las que mayor número de especies posee en el reino Plantae, con aproximadamente 900 géneros, de los cuales, el 38% es endémico de Colombia, concentrado en la región Andina, con 87,2%. Esta investigación buscó profundizar en el tema de la propagación como mecanismo de conservación, para lo cual, se determinó el efecto de la 6-Bencilaminopurina (6-BAP), sobre el desarrollo in vitro, en Fusagasugá (Cundinamarca), en un diseño de bloques completamente al azar, con 3 repeticiones. Cuerpos protocórmicos provenientes de semillas recolectadas en Pacho (Cundinamarca) fueron sembrados en medio básico Murashige & Skoog, enriquecido con 4 concentraciones de 6-BAP. Los resultados mostraron respuestas diferenciales a la adición de la citoquinina, ya que, con la concentración más alta, se obtuvo el mayor porcentaje de callos, con la de 0,05mg.L-1, el mayor porcentaje de brotes y sin la aplicación del regulador de crecimiento, el mayor porcentaje de raíz.The orchid Cattleya trianae Linden & Rchb.f. is recognized as the national flower of Colombia, the species is in a critical danger, presenting an estimated reduction of more than 80% in the last 100 years due to the decrease in habitat quality and high levels of exploitation or harvesting. The Orchidaceae family is one of the largest number of species in the Plant Kingdom, with approximately 900 genera, of which 38% are endemic in Colombia, concentrated in the Andean region with 87.2%. This research sought to deepen in the topic of the propagation as mechanism of protection for their conservation, for which the effect of cytokinin 6-benzylaminopurine (6-BAP) on development was determined in vitro in Fusagasugá (Cundinamarca), in a completely randomized block design with 3 replicates. The protocorm-like bodies from seeds collected in Pacho (Cundinamarca) were sown in a basic medium Murashige and Skoog enriched with 4 concentrations of 6-BAP. The results showed differential responses to the addition of cytokinin, as the highest concentration was obtained the highest percentage of callus, with the 0.05mg. L-1, the highest percentage of shoots and without the application of the growth regulator, the highest root percentage.Incluye referencias bibliográfica
Plasma Rich in Growth Factors Membrane as Coadjuvant Treatment in the Surgery of Ocular Surface Disorders
To evaluate the safety and efficacy of the surgical use of plasma rich in growth factors fibrin membrane (mPRGF) in different ocular surface pathologies.Fifteen patients with different corneal and conjunctival diseases were included in the study. Patients were grouped according to the use of mPRGF as graft (corneal and/or conjunctival) or dressing; they were also grouped according to the surgical subgroup of intervention (persistent corneal ulcer [PCU], keratoplasty, superficial keratectomy, corneal perforation, and pterygium). Best corrected visual acuity, intraocular pressure (IOP), inflammation control time (ICT), mPRGF AT (PRGF membrane absorption time), and the healing time of the epithelial defect (HTED) were evaluated throughout the clinical follow-up time. Safety assessment was also performed reporting all adverse events.mPRGF showed a total closure of the defect in 13 of 15 patients (86.7%) and a partial closure in 2 patients (13.3%). The mean follow-up time was 11.14.2 (4.8-22.8) months, the mean ICT was 2.5 +/- 1.1 (1.0-4.0) months, the mean mPRGF AT was 12.4 +/- 2.0 (10.0-16.0) days, and for the global HTED the mean was 2.9 +/- 1.2 (1-4.8) months. Results showed an improvement in BCVA in all patients, with an overall improvement of 2.9 in Vision Lines. The BCVA significantly improved (P.05) throughout the clinical follow-up time. No adverse events were reported after mPRGF use.The mPRGF is effective and safe as coadjuvant treatment in surgeries related with ocular surface disorders, being an alternative to the use of amniotic membrane. The mPRGF accelerates tissue regeneration after ocular surface surgery thus minimizing inflammation and fibrosis.This study received funding from the Ministry of Economy and Competitiveness of the Spanish Government, within the project denominated SURFEYE (reference RTC-2014-2375-1)
Macromolecular crowding links ribosomal protein gene dosage to growth rate in Vibrio cholerae
In fast-growing bacteria, the genomic location of ribosomal protein (RP) genes is biased towards the replication origin (oriC). This trait allows optimizing their expression during exponential phase since oriC neighboring regions are in higher dose due to multifork replication. Relocation of s10-spc-α locus (S10), which codes for most of the RP, to ectopic genomic positions shows that its relative distance to the oriC correlates to a reduction on its dosage, its expression, and bacterial growth rate. However, a mechanism linking S10 dosage to cell physiology has still not been determined.We hypothesized that S10 dosage perturbations impact protein synthesis capacity. Strikingly, we observed that in Vibrio cholerae, protein production capacity was independent of S10 position. Deep sequencing revealed that S10 relocation altered chromosomal replication dynamics and genome-wide transcription. Such changes increased as a function of oriC-S10 distance. Since RP constitutes a large proportion of cell mass, lower S10 dosage could lead to changes in macromolecular crowding, impacting cell physiology. Accordingly, cytoplasm fluidity was higher in mutants where S10 is most distant from oriC. In hyperosmotic conditions, when crowding differences are minimized, the growth rate and replication dynamics were highly alleviated in these strains.The genomic location of RP genes ensures its optimal dosage. However, besides of its essential function in translation, their genomic position sustains an optimal macromolecular crowding essential for maximizing growth. Hence, this could be another mechanism coordinating DNA replication to bacterial growth.Fil: Soler Bistue, Alfonso J. C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; ArgentinaFil: Aguilar Pierlé, Sebastián. Institut Pasteur; FranciaFil: Garcia Garcerá, Marc. Institut Pasteur; FranciaFil: Val, Marie Eve. Institut Pasteur; FranciaFil: Sismeiro, Odile. Institut Pasteur; FranciaFil: Varet, Hugo. Institut Pasteur; FranciaFil: Sieira, Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Krin, Evelyne. Institut Pasteur; FranciaFil: Skovgaard, Ole. Roskilde Universitet; DinamarcaFil: Comerci, Diego José. Universidad Nacional de San Martin. Instituto de Investigaciones Biotecnologicas. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Investigaciones Biotecnologicas.; ArgentinaFil: Rocha, Eduardo P. C.. Institut Pasteur; FranciaFil: Mazel, Didier. Institut Pasteur; Franci
Heterosexual oral and anal sex in Kinshasa (D.R.Congo): Data from OKAPI prospective cohort
Background
Sexually transmitted infections can be spread through oral and anal heterosexual sex. There are few data on these practices in Sub-Saharan Africa. We analyzed the prevalence of heterosexual oral and anal sex among HIV Voluntary Counseling and Testing (VCT) attendees in Kinshasa and the associated sociodemographics, perceptions and behavioral factors.
Methods
OKAPI (Observational Kinshasa AIDS Prevention Initiative) prospective cohort study. It evaluates the VCT impact on HIV-related knowledge and behaviors at 6 and 12-month follow-up. Since April 2016 until April 2018, 797 persons aged 15–59 years were HIV tested and replied to a baseline interview, including information about anal and oral sex. Descriptive, bi- and multivariate analyses were performed using baseline data.
Results
Among 718 sexually active participants reporting heterosexual sex, 59% had had oral sex, 22% anal sex and 18% both practices. Among participants reporting “not” having had sex, 6% reported oral sex, 3% anal sex and 1% both. Oral sex was associated with a daily use of the Internet/mobile phone, perceiving low community HIV risk, reporting HIV-related behaviors (multiple partners, inconsistent condom use, anal, paid and forced sex) and having been pregnant. Being married-monogamous was inversely associated with oral sex. Anal sex was directly associated with having other risk sexual behaviors.
Conclusions
Oral and anal sex were common among people reporting heterosexual sex in Kinshasa. Perceiving a low community HIV risk and having other sexual risk behaviors are associated with these practices, which are commonly not considered as risky despite their strong association with HIV/STIs. They need to be considered when designing preventive strategies in Kinshasa
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