135 research outputs found
The Luminosity Function of Magnitude and Proper-Motion Selected Samples. The case of White-Dwarfs
The luminosity function of white dwarfs is a powerful tool for studies of the
evolution and formation of the Milky Way. The (theoretical) white dwarf cooling
sequence provides a useful indicator of the evolutionary time scales involved
in the chronometry and star formation history of the galactic disk, therefore,
intrinsically faint (& old) white dwarfs in the immediate solar neighborhood
can be used to determine an upper limit for the age of the galactic disk.
In this paper we examine the faint-end () behavior of the disk
white dwarf luminosity function using the method, but fully
including the effects of realistic observational errors in the derived
luminosity function. We employ a Monte Carlo approach to produce many different
realizations of the luminosity function from a given data set with
pre-specified and reasonable errors in apparent magnitude, proper-motions,
parallaxes and bolometric corrections. These realizations allow us to compute
both a mean and an expected range in the luminosity function that is compatible
with the observational errors.
We find that current state-of-the art observational errors, mostly in the
bolometric corrections and trigonometric parallaxes, play a major role in
obliterating (real or artificial) small scale fluctuations in the luminosity
function. We also find that a better estimator of the true luminosity function
seems to be the median over simulations, rather than the mean. When using the
latter, an age for the disk of 10 Gyr or older can not be ruled out from the
sample of Leggett, Ruiz, and Bergeron (1998).Comment: Manuscript AAS Latex macro v4.0, 33 pages, 13 postscript figures
(Color in figs. 9 and 12). Accepted for publication in The Astrophysical
Journal. Replaced by two-column version & indication of acceptance by the Ap
Detección del virus papiloma humano (HPV) y citología de Papanicolaou en mujeres de bajos recursos de la ciudad de Posadas, Misiones, Argentina
El objetivo de este estudio fue determinar la prevalencia de la infección por HPV y de lesiones cervicales en mujeres asistidas en un centro de salud situado en un área de bajos recursos de la ciudad de Posadas, Misiones, Argentina. Las muestras (n = 163) fueron examinadas mediante las pruebas de Papanicolaou y de PCR para HPV. Los factores socio-culturales de riesgo fueron identifcados mediante el cálculo de la odds ratio (OR, IC 95 %). Se detectaron lesiones cervicales en el 14,7 % de las mujeres. La prevalencia de infección por HPV fue de 38 %. Los tipos más frecuentes en la población total fueron HPV-16 (9,8 %) y HPV-33 (9,3 %). El HPV-16 se detectó asociado al 29,2 % y al 6,5 % de las mujeres con lesiones del cuello uterino y sin ellas, respectivamente, con un OR de 5,3 (1,8-15,8). Los factores de riesgo para la infección por HPV-16 fueron el hábito de fumar y el antecedente de enfermedades de transmisión sexual. Estos datos son importantes para la ejecución de los programas de prevención, incluyendo una introducción adecuada de la vacunación y la línea de base para la vigilancia virológica en la era de la vacuna.The objective of this study was to determine the prevalence of HPV infection and cervical lesions present in women who attended a health center in a low-resource area of the city of Posadas, Misiones, Argentina. Cervical cell samples (n = 163) were processed for Papanicolaou cytology and HPV-PCR tests. Socio-cultural risk factors were estimated using the odds ratio (OR, CI 95 %). Cervical lesions were detected in 14.7 % of women. The general prevalence of HPV infection was of 38 %. The most common types among the total population were HPV-16 (9.8 %) and HPV-33 (9.3 %). HPV-16 was detected in association with 29.2 % and 6.5 % of women with and without cervical lesions, respectively, the OR being 5.3 (1.8-15.8). Risk factors for HPV-16 infection were a smoking habit and a history of previous sexually-transmitted diseases. These data are important for the implementation of prevention programs, including an appropriate introduction of vaccination and the baseline for virological surveillance in the vaccine era.Fil: Badano, Ines. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Laboratorio de Biología Molecular Aplicada; ArgentinaFil: Pedrozo, Rene W.. Provincia de Misiones. Ministerio de Salud de la Provincia de Misiones; ArgentinaFil: Ruiz Diaz, Laura S.. Provincia de Misiones. Ministerio de Salud de la Provincia de Misiones; ArgentinaFil: Galuppo, Juan A.. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Laboratorio de Biología Molecular Aplicada; ArgentinaFil: Picconi, María A.. Direccion Nacional de Instituto de Investigacion. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbran". Instituto Nacional de Enfermedades Infecciosas. Departamento de Virologia; ArgentinaFil: Campos, Rodolfo Hector. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Liotta, Domingo Javier. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Laboratorio de Biología Molecular Aplicada; Argentin
Selective and mild fractionation of microalgal proteins and pigments using aqueous two-phase systems
publishedVersionPaid Open Acces
Multistep Fractionation of Microalgal Biomolecules Using Selective Aqueous Two-Phase Systems
We aim to develop liquid-liquid extraction processes for the fractionation of microalgal components (proteins, pigments, lipids, and carbohydrates). The partitioning behavior of microalgal pigments and proteins in aqueous two-phase systems (ATPS) composed of the polymer polypropylene glycol with molecular weight 400 (PPG 400) + various cholinium based-ionic liquids was studied. A process for fractionation of multiple components from disrupted Neochloris oleoabundans was developed and evaluated. Results show that cholinium dihydrogen phosphate (Ch DHp) allows the fractionation of pigments in the PPG 400-rich phase and proteins in the Ch DHp-rich phase with high selectivity. It was demonstrated that a multiproduct approach can fractionate free glucose, and proteins in the ionic liquid-rich phase, pigments in the polymer-rich phase, while starch and lipids are recovered at the interface.</p
Fractionation of proteins and carbohydrates from crude microalgae extracts using an ionic liquid based-aqueous two phase system
publishedVersionPaid Open Acces
Selective fractionation of free glucose and starch from microalgae using aqueous two-phase systems
Microalgae are a promising source of lipids, pigments, proteins and carbohydrates, which are valuable compounds for many industries. However, optimal fractionation and valorization of all produced compounds is necessary to improve the economic viability of microalgae production. This paper aims to understand the fractionation of microalgae carbohydrates (free glucose and starch) in aqueous two-phase systems. Three aqueous two-phase systems were investigated to efficiently and mildly separate carbohydrates from disrupted Neochloris oleoabundans. This strain contains 16 w/w% of proteins, 48 w/w% total fatty acids and 27 w/w% carbohydrates when cultivated under saline water and nitrogen depletion conditions. The protein content decreases and the amount of fatty acids and carbohydrates increases notably under stress conditions and glucose becomes the main carbohydrate in this microalgae. Glucose is present in the disrupted microalgae as part of polymeric carbohydrates (starch) or in monomeric form (free glucose). With the aqueous two-phase system Polyethylene Glycol 400 - Cholinium dihydrogen phosphate (PEG400-ChDHp) microalgal free glucose is fractionated up to a recovery of 99% to the most hydrated bottom phase in a single step. Simultaneously, a recovery of 70% is reached for microalgal starch in the interface after two additional liquid-liquid extractions with PEG400-ChDHp. The final fractions obtained were free of pigments.publishedVersionPaid Open Acces
Molecular imaging of atherosclerotic plaque targeted to oxidized LDL receptor LOX-1 using magnetic resonance
Extensive preclinical validation of combined RMC-4550 and LY3214996 supports clinical investigation for KRAS mutant pancreatic cancer
Over 90% of pancreatic cancers present mutations in KRAS, one of the most common oncogenic drivers overall. Currently, most KRAS mutant isoforms cannot be targeted directly. Moreover, targeting single RAS downstream effectors induces adaptive resistance mechanisms. We report here on the combined inhibition of SHP2, upstream of KRAS, using the allosteric inhibitor RMC-4550 and of ERK, downstream of KRAS, using LY3214996. This combination shows synergistic anti-cancer activity in vitro, superior disruption of the MAPK pathway, and increased apoptosis induction compared with single-agent treatments. In vivo, we demonstrate good tolerability and efficacy of the combination, with significant tumor regression in multiple pancreatic ductal adenocarcinoma (PDAC) mouse models. Finally, we show evidence that 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) can be used to assess early drug responses in animal models. Based on these results, we will investigate this drug combination in the SHP2 and ERK inhibition in pancreatic cancer (SHERPA; ClinicalTrials.gov: NCT04916236) clinical trial, enrolling patients with KRAS-mutant PDAC.This work was funded by the American Association for Cancer Research, Lustgarten Foundation, and Stand Up to Cancer as a Pancreatic Cancer Collective New Therapies Challenge grant (grant no. SU2C-AACR-PCC-01-18)
Catching Element Formation In The Act
Gamma-ray astronomy explores the most energetic photons in nature to address
some of the most pressing puzzles in contemporary astrophysics. It encompasses
a wide range of objects and phenomena: stars, supernovae, novae, neutron stars,
stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays
and relativistic-particle acceleration, and the evolution of galaxies. MeV
gamma-rays provide a unique probe of nuclear processes in astronomy, directly
measuring radioactive decay, nuclear de-excitation, and positron annihilation.
The substantial information carried by gamma-ray photons allows us to see
deeper into these objects, the bulk of the power is often emitted at gamma-ray
energies, and radioactivity provides a natural physical clock that adds unique
information. New science will be driven by time-domain population studies at
gamma-ray energies. This science is enabled by next-generation gamma-ray
instruments with one to two orders of magnitude better sensitivity, larger sky
coverage, and faster cadence than all previous gamma-ray instruments. This
transformative capability permits: (a) the accurate identification of the
gamma-ray emitting objects and correlations with observations taken at other
wavelengths and with other messengers; (b) construction of new gamma-ray maps
of the Milky Way and other nearby galaxies where extended regions are
distinguished from point sources; and (c) considerable serendipitous science of
scarce events -- nearby neutron star mergers, for example. Advances in
technology push the performance of new gamma-ray instruments to address a wide
set of astrophysical questions.Comment: 14 pages including 3 figure
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