639 research outputs found
Optimal villi density for maximal oxygen uptake in the human placenta
We present a stream-tube model of oxygen exchange inside a human placenta
functional unit (a placentone). The effect of villi density on oxygen transfer
efficiency is assessed by numerically solving the diffusion-convection equation
in a 2D+1D geometry for a wide range of villi densities. For each set of
physiological parameters, we observe the existence of an optimal villi density
providing a maximal oxygen uptake as a trade-off between the incoming oxygen
flow and the absorbing villus surface. The predicted optimal villi density
is compatible to previous experimental measurements. Several
other ways to experimentally validate the model are also proposed. The proposed
stream-tube model can serve as a basis for analyzing the efficiency of human
placentas, detecting possible pathologies and diagnosing placental health risks
for newborns by using routine histology sections collected after birth
Highly-functionalised difluorinated cyclohexane polyols via the Diels–Alder reaction : regiochemical control via the phenylsulfonyl group
A difluorinated dienophile underwent cycloaddition reactions with a range of furans to afford cycloadducts whichcould be processed regio- and stereoselectively via episulfonium ions, generated by the reaction between their alkenyl groups and phenylsulfenyl chloride. The oxabicyclic products were oxidised to the phenylsulfonyl level and ring opened via E1CB or reductive desulfonative pathways to afford, ultimately, difluorinated cyclohexene or cyclohexane polyols
Gamma-ray burst jet propagation, development of angular structure, and the luminosity function
The fate and observable properties of gamma-ray burst jets depend crucially
on their interaction with the progenitor material that surrounds the central
engine. We present a semi-analytical model of such interaction, which builds
upon several previous analytical and numerical works, aimed at predicting the
angular distribution of jet and cocoon energy and Lorentz factor after
breakout, given the properties of the ambient material and of the jet at
launch. Using this model, we construct synthetic populations of structured
jets, assuming either a collapsar (for long gamma-ray bursts -- LGRBs) or a
binary neutron star merger (for short gamma-ray bursts -- SGRBs) as progenitor.
We assume all progenitors to be identical, and we allow little variability in
the jet properties at launch: our populations therefore feature a
quasi-universal structure. These populations are able to reproduce the main
features of the observed LGRB and SGRB luminosity functions, although several
uncertainties and caveats remain to be addressed.Comment: 15 pages, 12 figures. Revised version, submitted to A&A (several new
figures and expanded discussion. Conclusions unchanged). Comments and
suggestions are welcome
Diagnóstico molecular de Neisseria gonorrhoeae en Mendoza
Neisseria gonorrheae es una bacteria de transmisión sexual que afecta exclusivamente a humanos. Esta bacteria coloniza las mucosas de la uretra, endocervix, tubo de Falopio, recto, conjuntiva faríngea. Las infecciones causadas en el aparato genital varían desde infecciones agudas de resolución favorable hasta enfermedad inflamatoria pélvica que cronifica provocando secuelas irreversibles como obstrucción tubárica y esterilidad. Incrementa además hasta 5 veces la transmisión del virus HIV. Entre otras implicaciones críticas en la salud reproductiva, también pueden causar embarazos ectópicos, abortos en el primer trimestre del embarazo y como se mencionó antes, esterilidad. El mayor riesgo para el recién nacido son las infecciones oculares que pueden derivar en ceguera.
La gonorrea es la segunda enfermedad de transmisión sexual de origen bacteriano más frecuente en el mundo En los últimos años se han incrementado el número de individuos infectados y la aparición de cepas resistentes a los antibióticos utilizados. La situación en Mendoza sigue las tendencias mundiales. Para su detección en la provincia se utilizan técnicas de cultivo. La detección temprana y rápida, por medio de la Reacción en Cadena de la Polimerasa es una herramienta necesaria para su diagnóstico
Electromagnetic counterparts of black hole-neutron star mergers: dependence on the neutron star properties
Detections of gravitational waves (GWs) may soon uncover the signal from the
coalescence of a black hole - neutron star (BHNS) binary, that is expected to
be accompanied by an electromagnetic (EM) signal. In this paper, we present a
composite semi-analytical model to predict the properties of the expected EM
counterpart from BHNS mergers, focusing on the kilonova emission and on the
gamma-ray burst afterglow. Four main parameters rule the properties of the EM
emission: the NS mass , its tidal deformability
, the BH mass and spin. Only for certain combinations of
these parameters an EM counterpart is produced. Here we explore the parameter
space, and construct light curves, analysing the dependence of the EM emission
on the NS mass and tidal deformability. Exploring the NS parameter space
limiting to pairs described by a physically
motivated equations of state (EoS), we find that the brightest EM counterparts
are produced in binaries with low mass NSs (fixing the BH properties and the
EoS). Using constraints on the NS EoS from GW170817, our modeling shows that
the emission falls in a narrow range of absolute magnitudes. Within the range
of explored parameters, light curves and peak times are not dissimilar to those
from NSNS mergers, except in the B band. The lack of an hyper/supra-massive NS
in BHNS coalescences causes a dimming of the blue kilonova emission in absence
of the neutrino interaction with the ejecta.Comment: 22 pages, 20 figures. Accepted for publication on EPJA, in Topical
Issue "First joint gravitational wave and electromagnetic observations:
Implications for nuclear and particle physics
Green Extraction Approaches for Carotenoids and Esters: Characterization of Native Composition from Orange Peel
Abstract: Orange peel is a by-product produced in large amounts that acts as a source of natural pigments such as carotenoids. Xanthophylls, the main carotenoid class found in citrus fruit, can be present in its free form or esterified with fatty acids, forming esters. This esterification modifies the compound’s chemical properties, affecting their bioavailability in the human body, and making it important to characterize the native carotenoid composition of food matrices. We aimed to evaluate the non-saponified carotenoid extracts of orange peel (cv. Pera) obtained using alternative green approaches: extraction with ionic liquid (IL), analyzed by high performance liquid chromatography coupled to a diode array detector with atmospheric pressure chemical ionization and mass spectrometry HPLC-DAD-APCI-MS, and supercritical fluid extraction (SFE), followed by supercritical fluid chromatography with atmospheric pressure chemical ionization and triple quadrupole mass spectrometry detection (SFC-APCI/QqQ/MS) in an online system. Both alternative green methods were successfully applied, allowing the total identification of five free carotenoids, one apocarotenoid, seven monoesters, and 11 diesters in the extract obtained with IL and analyzed by HPLC-DAD-APCI-MS, and nine free carotenoids, six carotenoids esters, 19 apocarotenoids, and eight apo-esters with the SFE-SFC-APCI/QqQ/MS approach, including several free apocarotenoids and apocarotenoid esters identified for the first time in oranges, and particularly in the Pera variety, which could be used as a fruit authenticity parameter.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Bioscience Department, Universidade Federal de São Paulo, Rua Silva Jardin 136, 11015-020 Santos, BrazilDepartment of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Polo Annunziata, Viale Annunziata, 98168 Messina, ItalyDepartment of Mathematical and Computer Science, Physical Sciences and Earth Sciences, University of Messina, 98168 Messina, ItalyFederal Institute of São Paulo, Av. Clara Gianotti de Souza 5180, 11900-000 Registro, BrazilChemistry Department, Federal University of São Carlos, Rodovia Washington Luíz, Km 235, 13565-905 São Carlos, BrazilChromaleont s.r.l., c/o Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, ItalyBeSep s.r.l., c/o Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, ItalyUnit of Food Science and Nutrition, Department of Medicine, University Campus Bio-Medico of Rome, 00128 Rome, ItalyDepartment of Biomedical, Dental, Morphological and Functional Imaging Sciences, University of Messina, Via Consolare Valeria, 98125 Messina, ItalyBioscience Department, Universidade Federal de São Paulo, Rua Silva Jardin 136, 11015-020 Santos, BrazilFAPESP: 2015/26789-5FAPESP: 2016/18910-1FAPESP: 2017/20861-1FAPESP: 2019/25303-
Acute Histologic Chorioamnionitis at Term: Nearly Always Noninfectious
Background: The link between histologic acute chorioamnionitis and infection is well established in preterm deliveries, but less well-studied in term pregnancies, where infection is much less common. Methodology/Principal Findings We conducted a secondary analysis among 195 low-risk women with term pregnancies enrolled in a randomized trial. Histologic and microbiologic evaluation of placentas included anaerobic and aerobic cultures (including mycoplasma/ureaplasma species) as well as PCR. Infection was defined as ≥1,000 cfu of a single known pathogen or a ≥2 log difference in counts for a known pathogen versus other organisms in a mixed culture. Placental membranes were scored and categorized as: no chorioamnionitis, Grade 1 (subchorionitis and patchy acute chorioamnionitis), or Grade 2 (severe, confluent chorioamnionitis). Grade 1 or grade 2 histologic chorioamnionitis was present in 34% of placentas (67/195), but infection was present in only 4% (8/195). Histologic chorioamnionitis was strongly associated with intrapartum fever >38°C [69% (25/36) fever, 26% (42/159) afebrile, P<.0001]. Fever occurred in 18% (n = 36) of women. Most febrile women [92% (33/36)] had received epidural for pain relief, though the association with fever was present with and without epidural. The association remained significant in a logistic regression controlling for potential confounders (OR = 5.8, 95% CI = 2.2,15.0). Histologic chorioamnionitis was also associated with elevated serum levels of interleukin-8 (median = 1.3 pg/mL no histologic chorioamnionitis, 1.5 pg/mL Grade 1, 2.1 pg/mL Grade 2, P = 0.05) and interleukin-6 (median levels = 2.2 pg/mL no chorioamnionitis, 5.3 pg/mL Grade 1, 24.5 pg/mL Grade 2, P = 0.02) at admission for delivery as well as higher admission WBC counts (mean = 12,000cells/mm no chorioamnionitis, 13,400cells/mm Grade 1, 15,700cells/mm Grade 2, P = 0.0005). Conclusion/Significance: Our results suggest histologic chorioamnionitis at term most often results from a noninfectious inflammatory process. It was strongly associated with fever, most of which was related to epidural used for pain relief. A more ‘activated’ maternal immune system at admission was also associated with histologic chorioamnionitis
The brightest GRB ever detected: GRB 221009A as a highly luminous event at z = 0.151
Context: The extreme luminosity of gamma-ray bursts (GRBs) makes them
powerful beacons for studies of the distant Universe. The most luminous bursts
are typically detected at moderate/high redshift, where the volume for seeing
such rare events is maximized and the star-formation activity is greater than
at z = 0. For distant events, not all observations are feasible, such as at TeV
energies.
Aims: Here we present a spectroscopic redshift measurement for the
exceptional GRB 221009A, the brightest GRB observed to date with emission
extending well into the TeV regime.
Methods: We used the X-shooter spectrograph at the ESO Very Large Telescope
(VLT) to obtain simultaneous optical to near-IR spectroscopy of the burst
afterglow 0.5 days after the explosion.
Results: The spectra exhibit both absorption and emission lines from material
in a host galaxy at z = 0.151. Thus GRB 221009A was a relatively nearby burst
with a luminosity distance of 745 Mpc. Its host galaxy properties
(star-formation rate and metallicity) are consistent with those of LGRB hosts
at low redshift. This redshift measurement yields information on the energy of
the burst. The inferred isotropic energy release, erg, lies at the high end of the distribution, making GRB 221009A one
of the nearest and also most energetic GRBs observed to date. We estimate that
such a combination (nearby as well as intrinsically bright) occurs between once
every few decades to once per millennium.Comment: 9 pages, 4 figures, submitted to Astronomy & Astrophysic
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