Reproducibility of extracellular vesicle research

Publisher Copyright: © 2022Cells release membrane-delimited particles into the environment. These particles are called “extracellular vesicles” (EVs), and EVs are present in fluids contacting cells, including body fluids and conditioned culture media. Because EVs change and contribute to health and disease, EVs have become a hot topic. From the thousands of papers now published on EVs annually, one easily gets the impression that EVs provide biomarkers for all diseases, and that EVs are carriers of all relevant biomolecules and are omnipotent therapeutics. At the same time, EVs are heterogeneous, elusive and difficult to study due to their physical properties and the complex composition of their environment. This overview addresses the current challenges encountered when working with EVs, and how we envision that most of these challenges will be overcome in the near future. Right now, an infrastructure is being developed to improve the reproducibility of EV measurement results. This infrastructure comprises expert task forces of the International Society of Extracellular Vesicles (ISEV) developing guidelines and recommendations, instrument calibration, standardized and transparent reporting, and education. Altogether, these developments will support the credibility of EV research by introducing robust reproducibility, which is a prerequisite for understanding their biological significance and biomarker potential.Peer reviewe

Carbon stars in the X-shooter Spectral Library

We provide a new collection of spectra of 35 carbon stars obtained with the ESO/VLT X-shooter instrument as part of the X-shooter Spectral Library project. The spectra extend from 0.3$\mu$m to 2.4$\mu$m with a resolving power above $\sim$ 8000. The sample contains stars with a broad range of (J-K) color and pulsation properties located in the Milky Way and the Magellanic Clouds. We show that the distribution of spectral properties of carbon stars at a given (J-K) color becomes bimodal (in our sample) when (J-K) is larger than about 1.5. We describe the two families of spectra that emerge, characterized by the presence or absence of the absorption feature at 1.53$\mu$m, generally associated with HCN and C$_2$H$_2$. This feature appears essentially only in large-amplitude variables, though not in all observations. Associated spectral signatures that we interpret as the result of veiling by circumstellar matter, indicate that the 1.53$\mu$m feature might point to episodes of dust production in carbon-rich Miras.Comment: 29 pages, 21 figures, 9 tables, Accepted for publication in A&

Testing models with non-minimal Higgs sector through the decay t->q+WZ

We study the contribution of charged Higgs boson to the rare decay of the top quark t->q+WZ (q=d,s,b) in models with Higgs sector that includes doublets and triplets. Higgs doublets are needed to couple charged Higgs with quarks, whereas the Higgs triplets are required to generate the non-standard vertex HWZ at tree-level. It is found that within a model that respect the custodial SU(2) symmetry and avoids flavour changing neutral currents by imposing discrete symmetries, the decay mode t->b+WZ, can reach a branching ratio of order 0.0178, whereas the decay modes t->(d,s)+WZ, can reach a similar branching ratio in models where flavour changing neutral currents are suppressed by flavour symmetries.Comment: Typeset using REVTEX and EPSF, 5 pag, 2 figure

Coherent deglacial changes in western Atlantic Ocean circulation

Abrupt climate changes in the past have been attributed to variations in Atlantic Meridional Overturning Circulation (AMOC) strength. However, the exact timing and magnitude of past AMOC shifts remain elusive, which continues to limit our understanding of the driving mechanisms of such climate variability. Here we show a consistent signal of the 231Pa/230Th proxy that reveals a spatially coherent picture of western Atlantic circulation changes over the last deglaciation, during abrupt millennial-scale climate transitions. At the onset of deglaciation, we observe an early slowdown of circulation in the western Atlantic from around 19 to 16.5 thousand years ago (ka), consistent with the timing of accelerated Eurasian ice melting. The subsequent weakened AMOC state persists for over a millennium (~16.5–15 ka), during which time there is substantial ice rafting from the Laurentide ice sheet. This timing indicates a role for melting ice in driving a two-step AMOC slowdown, with a positive feedback sustaining continued iceberg calving and climate change during Heinrich Stadial 1NERC | Ref. NE/K008536/

La morosidad ante un confinamiento del Covid-19 en la Caja Rural de Ahorro y Crédito Raíz, Perú

Delinquency is a highly relevant variable for a financial institution, since through the delinquency index it allows to measure the performance of the entities. Therefore, the research has been carried out with the purpose of describing the evolution of delinquencies in the confinement of Covid-19, in the Rural Savings and Credit Root Fund. The study had a non-experimental design, with a quantitative and descriptive approach, the population consisted of 44 between agencies and offices distributed nationwide. Among the instruments applied was the document analysis guide. The results showed that the company between 2016 and 2020 delinquencies presented an increasing trend, due to microeconomic and macroeconomic factors, the latter due to the global crisis caused by Covid-19. Therefore, it is concluded that the increase in delinquencies between the analyzed period was influenced by the non-compliance of credit payments between the first 30 and 60 days, as a result of the purchasing deficit and / or conjunctural problems on the part of the clients, and currently due to the coronavirus pandemic in which the majority of Peruvians have been economically affected.La morosidad es una variable de gran relevancia para una entidad financiera, pues a través del índice de morosidad permite medir el desempeño de las entidades. Por lo que la investigación se ha desarrollado con el propósito de describir la evolución de la morosidad ante un confinamiento del Covid-19 en la Caja Rural de Ahorro y Crédito Raíz. El estudio tuvo un diseño no experimental, con enfoque cuantitativo y de carácter descriptivo, la población estuvo conformada por 44 entre agencias y oficinas distribuidas a nivel nacional. Entre los instrumentos que se aplicó fue la guía de análisis documental. Los resultados mostraron que la empresa entre el 2016 al 2020 la morosidad presentó una tendencia creciente, producto de factores microeconómicos y macroeconómicos este último debido a la crisis mundial ocasionada por el Covid-19. Por lo tanto, se concluye que el aumento de la morosidad entre el periodo analizado estuvo influenciado por el incumplimiento de los pagos crediticios entre los primeros 30 y 60 días, producto del déficit adquisitivo y/o problemas coyunturales por parte de los clientes, y actualmente por la pandemia del coronavirus en la que la mayoría de los peruanos se ha visto afectada económicamente

The Einstein Cross: constraint on dark matter from stellar dynamics and gravitational lensing

[Abridged] We present two-dimensional line-of-sight stellar kinematics of the lens galaxy in the Einstein Cross, obtained with the GEMINI 8m telescope, using the GMOS integral-field spectrograph. The velocity map shows regular rotation up to ~100 km/s around the minor axis of the bulge, consistent with axisymmetry. The velocity dispersion map shows a weak gradient increasing towards a central (R<1") value of sigma_0=170+/-9 km/s. We deproject the observed surface brightness from HST imaging to obtain a realistic luminosity density of the lens galaxy, which in turn is used to build axisymmetric dynamical models that fit the observed kinematic maps. We also construct a gravitational lens model that accurately fits the positions and relative fluxes of the four quasar images. We find that the resulting luminous and total mass distribution are nearly identical around the Einstein radius R_E = 0.89", with a slope that is close to isothermal, but which becomes shallower towards the center if indeed mass follows light. The dynamical model fits to the observed kinematic maps result in a total mass-to-light ratio (M/L)_dyn=3.7+/-0.5 M_sun/L_sun,I (in the I-band). This is consistent with the Einstein mass M_E = 1.54 x 10^10 M_sun divided by the (projected) luminosity within R_E, which yields a total mass-to-light ratio of (M/L)_E=3.4 M_sun/L_sun,I, with an error of at most a few per cent. We estimate from stellar populations model fits to colors of the lens galaxy a stellar mass-to-light ratio (M/L)_* from 2.8 to 4.1 M_sun/L_sun,I. Although a constant dark matter fraction of 20 per cent is not excluded, dark matter may play no significant role in the bulge of this ~L* early-type spiral galaxy.Comment: 18 pages, 8 figures, published in ApJ, 2010, 719, 148

Atlantic reef fish biogeography and evolution

Copyright © 2007 The Authors.Journal compilation © 2007 Blackwell Publishing Ltd.AIM: To understand why and when areas of endemism (provinces) of the tropical Atlantic Ocean were formed, how they relate to each other, and what processes have contributed to faunal enrichment. RESULTS: Phylogenetic (proportion of sister species) and distributional (number of shared species) patterns are generally concordant with recognized biogeographical provinces in the Atlantic. The highly uneven distribution of species in certain genera appears to be related to their origin, with highest species richness in areas with the greatest phylogenetic depth. Diversity buildup in Atlantic reef fishes involved (1) diversification within each province, (2) isolation as a result of biogeographical barriers, and (3) stochastic accretion by means of dispersal between provinces. The timing of divergence events is not concordant among taxonomic groups. The three soft (non-terrestrial) inter-regional barriers (mid-Atlantic, Amazon, and Benguela) clearly act as ‘filters’ by restricting dispersal but at the same time allowing occasional crossings that apparently lead to the establishment of new populations and species. Fluctuations in the effectiveness of the filters, combined with ecological differences among provinces, apparently provide a mechanism for much of the recent diversification of reef fishes in the Atlantic

Nearby early-type galaxies with ionized gas. III. Analysis of line-strength indices with new stellar population models

In this paper we study the underlying stellar population of a sample of 65 nearby early-type galaxies predominantly located in low density environments. Ages, metallicities and [alpha/Fe] ratios have been derived through the comparison of Lick indices measured at different galacto-centric distances with new SSP models which account for the presence of alpha/Fe enhancement. The SSPs cover a wide range of ages, metallicities and [alpha/Fe] ratios. To derive the stellar population parameters we have devised an algorithm based on the probability density function. We derive a large spread in age ((1-15) Gyrs). Age does not show any significant trend with central velocity dispersion sigma_c but E galaxies appear on average older than S0. On the contrary, an increasing trend of metallicity and [alpha/Fe] with sigma_c is observed, testifying that the chemical enrichment was more efficient and the duration of the star formation shorter in more massive galaxies. We have also sought for possible correlations with the local galaxy density but neither metallicity nor alpha-enhancement show clear trends. However we find that while low density environments (LDE) contain very young objects (from 1 to 4 Gyr), none of the galaxies in the higher density environments (HDE) is younger than 5 Gyrs. Considering the lack of environmental effect on the [alpha/Fe] ratio and the high value of [alpha/Fe] in some young massive objects, we argue that young galaxies in LDE are more likely due to recent rejuvenation episodes. By comparing the number of rejuvenated objects with the total number of galaxies in our sample, and by means of simple two-SSP component models, we estimate that, on average, the rejuvenation episodes do not involve more than 25 % of the total galaxy mass.Comment: Final version as it will appear in A&A. Typos in the Abstract and Conclusions have been correcte

Cargo sorting to lysosome-related organelles regulates siRNA-mediated gene silencing

The activity of siRNAs in gene silencing is regulated by protein complexes that sort cargo to lysosome-related organelles