672 research outputs found

    The Complete Star Formation History of the Universe

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    The determination of the star-formation history of the Universe is a key goal of modern cosmology, as it is crucial to our understanding of how structure in the Universe forms and evolves. A picture has built up over recent years, piece-by-piece, by observing young stars in distant galaxies at different times in the past. These studies indicated that the stellar birthrate peaked some 8 billion years ago, and then declined by a factor of around ten to its present value. Here we report on a new study which obtains the complete star formation history by analysing the fossil record of the stellar populations of 96545 nearby galaxies. Broadly, our results support those derived from high-redshift galaxies elsewhere in the Universe. We find, however, that the peak of star formation was more recent - around 5 billion years ago. Our study also shows that the bigger the stellar mass of the galaxy, the earlier the stars were formed. This striking result indicates a very different formation history for high- and low-mass formation.Comment: Accepted by Nature. Press embargo until publishe

    Archaeosomes made of Halorubrum tebenquichense total polar lipids: a new source of adjuvancy

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    <p>Abstract</p> <p>Background</p> <p>Archaeosomes (ARC), vesicles prepared from total polar lipids (TPL) extracted from selected genera and species from the Archaea domain, elicit both antibody and cell-mediated immunity to the entrapped antigen, as well as efficient cross priming of exogenous antigens, evoking a profound memory response. Screening for unexplored Archaea genus as new sources of adjuvancy, here we report the presence of two new <it>Halorubrum tebenquichense </it>strains isolated from grey crystals (<it>GC</it>) and black mood (<it>BM</it>) strata from a littoral Argentinean Patagonia salt flat. Cytotoxicity, intracellular transit and immune response induced by two subcutaneous (sc) administrations (days 0 and 21) with BSA entrapped in ARC made of TPL either form <it>BM </it>(ARC-BM) and from <it>GC </it>(ARC-GC) at 2% w/w (BSA/lipids), to C3H/HeN mice (25 μg BSA, 1.3 mg of archaeal lipids per mouse) and boosted on day 180 with 25 μg of bare BSA, were determined.</p> <p>Results</p> <p>DNA G+C content (59.5 and 61.7% mol <it>BM </it>and <it>GC</it>, respectively), 16S rDNA sequentiation, DNA-DNA hybridization, arbitrarily primed fingerprint assay and biochemical data confirmed that <it>BM </it>and <it>GC </it>isolates were two non-previously described strains of <it>H. tebenquichense</it>. Both multilamellar ARC mean size were 564 ± 22 nm, with -50 mV zeta-potential, and were not cytotoxic on Vero cells up to 1 mg/ml and up to 0.1 mg/ml of lipids on J-774 macrophages (XTT method). ARC inner aqueous content remained inside the phago-lysosomal system of J-774 cells beyond the first incubation hour at 37°C, as revealed by pyranine loaded in ARC. Upon subcutaneous immunization of C3H/HeN mice, BSA entrapped in ARC-BM or ARC-GC elicited a strong and sustained primary antibody response, as well as improved specific humoral immunity after boosting with the bare antigen. Both IgG1 and IgG2a enhanced antibody titers could be demonstrated in long-term (200 days) recall suggesting induction of a mixed Th1/Th2 response.</p> <p>Conclusion</p> <p>We herein report the finding of new <it>H. tebenquichense </it>non alkaliphilic strains in Argentinean Patagonia together with the adjuvant properties of ARC after sc administration in mice. Our results indicate that archaeosomes prepared with TPL from these two strains could be successfully used as vaccine delivery vehicles.</p

    Neural response to monetary loss among youth with disruptive behavior disorders and callous-unemotional traits in the ABCD study

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    Etiological models highlight reduced punishment sensitivity as a core risk factor for disruptive behavior disorders (DBD) and callous-unemotional (CU) traits. The current study examined neural sensitivity to the anticipation and receipt of loss, one key aspect of punishment sensitivity, among youth with DBD, comparing those with and without CU traits. Data were obtained from the Adolescent Brain and Cognitive Development (ABCD)SM Study (N = 11,874; Mage = 9.51; 48% female). Loss-related fMRI activity during the monetary incentive delay task was examined across 16 empirically-derived a priori brain regions (e.g., striatum, amygdala, insula, anterior cingulate cortex, medial prefrontal cortex) and compared across the following groups: (1) typically developing (n = 693); (2) DBD (n = 995), subdivided into those (3) with CU traits (DBD + CU, n = 198), and (4) without CU traits (DBD-only, n = 276). Latent variable modeling was also employed to examine network-level activity. There were no significant between-group differences in brain activity to loss anticipation or receipt. Null findings were confirmed with and without covariates, using alternative grouping approaches, and in dimensional models. Network-level analyses also demonstrated comparable activity across groups during loss anticipation and receipt. Findings suggest that differences in punishment sensitivity among youth with DBD are unrelated to loss anticipation or receipt. More precise characterizations of other aspects punishment sensitivity are needed to understand risk for DBD and CU traits

    Lipoprotein Profiles in Class III Obese Caucasian and African American Women with Nonalcoholic Fatty Liver Disease

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    Triglyceride content in the liver is regulated by the uptake, production and elimination of lipoproteins, and derangements in these processes contribute to nonalcoholic fatty liver disease (NAFLD). Previous studies show a direct relationship between intrahepatic fat and production of apolipoprotein B100 (apoB100) containing particles, VLDL and LDL, but little consensus exists regarding changes in lipoprotein production in the development of simple steatosis (SS) versus nonalcoholic steatohepatitis (NASH). Further, ethnic variations in lipoproteins among SS and NASH are unknown as is how such variations might contribute to the differential prevalence of disease among Caucasians versus African Americans. In this study, we assessed plasma lipoprotein profiles by nuclear magnetic resonance (NMR) spectroscopy in 70 non-diabetic class III obese females recruited from the surgical weight loss clinic. Of these, 51 females were stratified by biopsy-staged NAFLD severity (histologically normal, SS, or NASH). NASH females displayed increased circulating triglycerides and increased VLDL particle number and size relative to those with histologically normal livers, while total and large LDL concentration decreased in SS versus NASH and correlated with increased insulin resistance (via HOMA2-IR). When Caucasian women were examined alone (n = 41), VLDL and triglycerides increased between normal and SS, while total LDL and apoB100 decreased between SS and NASH along with increased insulin resistance. Compared to Caucasians with SS, African American women with SS displayed reduced triglycerides, VLDL, and small LDL and a more favorable small to large HDL ratio despite having increased BMI and HOMA2-IR. These findings suggest that ApoB100 and lipoprotein subclass particle number and size can delineate steatosis from NASH in obese Caucasian females, but should be interpreted with caution in other ethnicities as African Americans with SS display relatively improved lipoprotein profiles. This may reflect variation in the relationship between dyslipidemia and NAFLD progression across gender and ethnicity

    Demonstration of Zero-touch Device and L3-VPN Service Management using the TeraFlow Cloud-native SDN Controller

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    We demonstrate zero-touch device bootstrapping, monitoring, and L3-VPN service management using the novel TeraFlow OS SDN controller prototype. TeraFlow aims at producing a cloud-native carrier-grade SDN controller offering scalability, extensibility, high-performance, and high-availability features

    A proposed analytical approach to estimate excess daily mortality rates in Ecuador

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    BackgroundThe COVID-19 pandemic has proved deadly all over the globe; however, one of the most lethal outbreaks occurred in Ecuador.AimsThis study aims to highlight the pandemic’s impact on the most affected countries worldwide in terms of excess deaths per capita and per day.MethodsAn ecological study of all-cause mortality recorded in Ecuador was performed. To calculate the excess deaths relative to the historical average for the same dates in 2017, 2018, and 2019, we developed a bootstrap method based on the central tendency measure of mean. A Poisson fitting analysis was used to identify trends on officially recorded all-cause deaths and COVID-19 deaths. A bootstrapping technique was used to emulate the sampling distribution of our expected deaths estimator μ⌢deaths by simulating the data generation and model fitting processes daily since the first confirmed case.ResultsIn Ecuador, during 2020, 115,070 deaths were reported and 42,453 were cataloged as excess mortality when compared to 2017–2019 period. Ecuador is the country with the highest recorded excess mortality in the world within the shortest timespan. In one single day, Ecuador recorded 1,120 deaths (6/100,000), which represents an additional 408% of the expected fatalities.ConclusionAdjusting for population size and time, the hardest-hit country due to the COVID-19 pandemic was Ecuador. The mortality excess rate shows that the SARS-CoV-2 virus spread rapidly in Ecuador, especially in the coastal region. Our results and the proposed new methodology could help to address the real situation of the number of deaths during the initial phase of pandemics

    Nanoinformatics: developing new computing applications for nanomedicine

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    Nanoinformatics has recently emerged to address the need of computing applications at the nano level. In this regard, the authors have participated in various initiatives to identify its concepts, foundations and challenges. While nanomaterials open up the possibility for developing new devices in many industrial and scientific areas, they also offer breakthrough perspectives for the prevention, diagnosis and treatment of diseases. In this paper, we analyze the different aspects of nanoinformatics and suggest five research topics to help catalyze new research and development in the area, particularly focused on nanomedicine. We also encompass the use of informatics to further the biological and clinical applications of basic research in nanoscience and nanotechnology, and the related concept of an extended ?nanotype? to coalesce information related to nanoparticles. We suggest how nanoinformatics could accelerate developments in nanomedicine, similarly to what happened with the Human Genome and other -omics projects, on issues like exchanging modeling and simulation methods and tools, linking toxicity information to clinical and personal databases or developing new approaches for scientific ontologies, among many others

    A characterization of ASAS-SN core-collapse supernova environments with VLT+MUSE: I. Sample selection, analysis of local environments, and correlations with light curve properties

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    The analysis of core-collapse supernova (CCSN) environments can provide important information on the life cycle of massive stars and constrain the progenitor properties of these powerful explosions. The MUSE instrument at the VLT enables detailed local environment constraints of the progenitors of large samples of CCSNe. Using a homogeneous SN sample from the ASAS-SN survey has enabled us to perform a minimally biased statistical analysis of CCSN environments. We analyze 111 galaxies observed by MUSE that hosted 112 CCSNe detected or discovered by the ASAS-SN survey between 2014 and 2018. The majority of the galaxies were observed by the the AMUSING survey. Here we analyze the immediate environment around the SN locations and compare the properties between the different CCSN types and their light curves. We used stellar population synthesis and spectral fitting techniques to derive physical parameters for all HII regions detected within each galaxy, including the star formation rate (SFR), Hα\alpha equivalent width (EW), oxygen abundance, and extinction. We found that stripped-envelope (SE) SNe occur in environments with a higher median SFR, Hα\alpha EW, and oxygen abundances than SNe II and SNe IIn/Ibn. The distributions of SNe II and IIn are very similar, indicating that these events explode in similar environments. For the SESNe, SNe Ic have higher median SFRs, Hα\alpha EWs, and oxygen abundances than SNe Ib. SNe IIb have environments with similar SFRs and Hα\alpha EWs to SNe Ib, and similar oxygen abundances to SNe Ic. We also show that the postmaximum decline rate, ss, of SNe II correlates with the Hα\alpha EW, and that the luminosity and the Δm15\Delta m_{15} parameter of SESNe correlate with the oxygen abundance, Hα\alpha EW, and SFR at their environments. This suggests a connection between the explosion mechanisms of these events to their environment properties
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