Accretion studies have been focused on the flow around bodies with point mass gravitational potentials, but few general results are available for non-point mass distributions. Here, we study the ...accretion flow onto non-divergent, core potentials moving through a background medium. We use Plummer and Hernquist potentials as examples to study gas accretion onto star clusters, dwarf and large galaxy halos, and galaxy clusters in a variety of astrophysical environments. The general conditions required for a core potential to collectively accrete large quantities of gas from the external medium are derived using both simulations and analytic results. The consequences of large mass accumulation in galaxy nuclei, dwarf galaxies, and star clusters are twofold. First, if the gas cools effectively star formation can be triggered, generating new stellar members in the system. Second, if the collective potential of the system is able to alter the ambient gas properties before the gas is accreted onto the individual core members, the augmented mass supply rates could significantly alter the state of the various accreting stellar populations and result in an enhanced central black hole accretion luminosity.
On 17 August 2017, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo interferometer detected gravitational waves (GWs) emanating from a binary neutron star merger, ...GW170817. Nearly simultaneously, the Fermi and INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) telescopes detected a gamma-ray transient, GRB 170817A. At 10.9 hours after the GW trigger, we discovered a transient and fading optical source, Swope Supernova Survey 2017a (SSS17a), coincident with GW170817. SSS17a is located in NGC 4993, an S0 galaxy at a distance of 40 megaparsecs. The precise location of GW170817 provides an opportunity to probe the nature of these cataclysmic events by combining electromagnetic and GW observations.
On 17 August 2017, Swope Supernova Survey 2017a (SSS17a) was discovered as the optical counterpart of the binary neutron star gravitational wave event GW170817. We report time-series spectroscopy of ...SSS17a from 11.75 hours until 8.5 days after the merger. Over the first hour of observations, the ejecta rapidly expanded and cooled. Applying blackbody fits to the spectra, we measured the photosphere cooling from
11,000
−
900
+
3400
to
9300
−
300
+
300
kelvin, and determined a photospheric velocity of roughly 30% of the speed of light. The spectra of SSS17a began displaying broad features after 1.46 days and evolved qualitatively over each subsequent day, with distinct blue (early-time) and red (late-time) components. The late-time component is consistent with theoretical models of r-process–enriched neutron star ejecta, whereas the blue component requires high-velocity, lanthanide-free material.
The aim of this work was to develop an air diffusion mesoporous carbon electrode (ADE-MC) as cathode for the in-situ electrogeneration of hydrogen peroxide and its application on electro-Fenton (EF) ...and solar photo electro-Fenton (SPEF) processes. Three different mesoporous carbon materials were obtained by organic-organic self-assembly synthesis (soft-template route) by changing concentrations of resorcinol-formaldehyde polymer as carbon precursor and Pluronic F-127™ surfactant as matrix-forming agent. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), linear voltammetry (LV) and linear rotating disk electrode voltammetry (LV-RDE). MC materials showed pore diameter between 3.6 and 4.6 nm. The efficiency of ADE-MC was explored as a function of H2O2 produced at current densities (50, 100 and 150 mA cm−2). The highest production of H2O2 was 10.85 mmol L−1 by applying 150 mA cm−2. Finally, the ADE-MC were used for the mineralization of amoxicillin (50 mg L−1), allowing complete degradation and mineralization percentages of 55% and 85% with EF and SPEF processes, respectively. MC electrodes produce H2O2 in enough amounts that provide a viable option to degradation and mineralization of others organic pollutants in aqueous media by EF and SPEF processes.
The merging neutron star gravitational-wave event GW170817 has been observed throughout the entire electromagnetic spectrum from radio waves to γ-rays. The resulting energetics, variability, and ...light curves are shown to be consistent with GW170817 originating from the merger of two neutron stars, in all likelihood followed by the prompt gravitational collapse of the massive remnant. The available γ-ray, X-ray, and radio data provide a clear probe for the nature of the relativistic ejecta and the non-thermal processes occurring within, while the ultraviolet, optical, and infrared emission are shown to probe material torn during the merger and subsequently heated by the decay of freshly synthesized r-process material. The simplest hypothesis, that the non-thermal emission is due to a low-luminosity short γ-ray burst (sGRB), seems to agree with the present data. While low-luminosity sGRBs might be common, we show here that the collective prompt and multi-wavelength observations are also consistent with a typical, powerful sGRB seen off-axis. Detailed follow-up observations are thus essential before we can place stringent constraints on the nature of the relativistic ejecta in GW170817.
Resumen Introducción y objetivo. La fractura nasal es la lesión facial más común y más del 50 % de todas las fracturas faciales en adultos. Debido a que en muchas ocasiones no es diagnosticada y ...tratada oportunamente, puede generar diferentes grados de limitación funcional y resultados estéticos indeseables. Pocos estudios evalúan la satisfacción de los pacientes tratados con técnica cerrada de reducción de fractura nasal. Nuestro objetivo es valorar la satisfacción funcional y estética posterior a reducción cerrada de fractura de huesos nasales en un hospital de Colombia, mediante la escala de evaluación de síntomas de obstrucción nasal (NOSE, por sus siglas en inglés - nasal obstruction symptom evaluation) y la escala estética subjetiva. Material y método. Estudio observacional analítico prospectivo de pacientes con fractura nasal llevados a reducción cerrada en el Hospital Universitario de Santander, Colombia. Se registraron las puntuaciones de las escalas NOSE y estética subjetiva, antes y 2 meses después de la cirugía. Resultados. Evaluamos 55 pacientes, 90.9% hombres. La mediana de edad fue de 31 años (RIC 24-48). El contexto de lesión principal fue violencia física (40%), seguido de accidente de tránsito (32.7%). Tras el procedimiento, los pacientes presentaron mejoría de obstrucción nasal medida con la escala NOSE (p<0.001); antes de la cirugía el 89% presentaba obstrucción nasal moderada-severa, posteriormente descendió a 14.5%. La escala NOSE mostró fabilidad por consistencia interna con alfa de Cronbach de 0.8317. Tras la cirugía hubo aumento de la satisfacción respecto al aspecto nasal (p<0.001). Conclusiones. En nuestro estudio, el cuestionario NOSE permitió cuantificar la mejora de síntomas de obstrucción nasal en pacientes con reducción cerrada por fractura de huesos nasales. Observamos mejoría de síntomas obstructivos nasales y aumento de satisfacción estética. Nivel de evidencia científica 4c Terapéutico
The COVID‐19 pandemic is responsible for millions of deaths worldwide yet its origin remains unclear. Two potential scenarios of how infection of humans initially occurred include zoonotic transfer ...from wild animals and a leak of the pathogen from a research laboratory. The Wuhan wet markets where wild animals are sold represent a strong scenario for zoonotic transfer. However, isolation of SARS‐CoV‐2 or its immediate predecessor from wild animals in their natural environment has yet to be documented. Due to incomplete evidence for a zoonotic origin, a laboratory origin is plausible. The Wuhan Institute of Virology is at the epicenter of the pandemic and their work has included manipulation of wild‐type coronavirus to enable infection of human cells. Although stronger evidence supports the zoonotic transfer, inconclusive reports maintain the laboratory leak hypothesis alive. It is imperative to reach a factual conclusion to prevent future pandemics.
Abstract
We present an analysis of the host-galaxy environment of Swope Supernova Survey 2017a (SSS17a), the discovery of an electromagnetic counterpart to a gravitational-wave source, GW170817. ...SSS17a occurred 1.9 kpc (in projection; 10.″2) from the nucleus of NGC 4993, an S0 galaxy at a distance of 40 Mpc. We present a
Hubble Space Telescope
(
HST
) pre-trigger image of NGC 4993,
Magellan
optical spectroscopy of the nucleus of NGC 4993 and the location of SSS17a, and broadband UV-through-IR photometry of NGC 4993. The spectrum and broadband spectral-energy distribution indicate that NGC 4993 has a stellar mass of
log
(
M
/
M
⊙
)
=
10.49
−
0.20
+
0.08
and star formation rate of 0.003
M
⊙
yr
−1
, and the progenitor system of SSS17a likely had an age of >2.8 Gyr. There is no counterpart at the position of SSS17a in the
HST
pre-trigger image, indicating that the progenitor system had an absolute magnitude
M
V
>
−
5.8
mag. We detect dust lanes extending out to almost the position of SSS17a and >100 likely globular clusters associated with NGC 4993. The offset of SSS17a is similar to many short gamma-ray-burst offsets, and its progenitor system was likely bound to NGC 4993. The environment of SSS17a is consistent with an old progenitor system such as a binary neutron star system.
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