The Arecibo Ultra-Deep Survey

The Arecibo Ultra Deep Survey (AUDS) is a blind HI survey aimed at detecting galaxies beyond the local Universe in the 21-cm emission line of neutral hydrogen (HI). The Arecibo L-band Feed Array (ALFA) was used to image an area of 1.35 deg2 to a redshift depth of 0.16, using a total on-source integration time of over 700 hours. The long integration time and small observation area makes it one of the most sensitive HI surveys, with a noise level of ∼75 μJy per 21.4 kHz (equivalent to 4.5 km s−1 at redshift z = 0). We detect 247 galaxies in the survey, more than doubling the number already detected in AUDS60. The mass range of detected galaxies is $\log (M_{\rm HI}~[h_{70}^{-2}{\rm M}_\odot ]) = 6.32 - 10.76$. A modified maximum likelihood method is employed to construct an HI mass function (HIMF). The best fitting Schechter parameters are: low-mass slope α = −1.37 ± 0.05, characteristic mass $\log (M^*~[h_{70}^{-2}{\rm M}_\odot ]) = 10.15 \pm 0.09$, and density $\Phi _* = (2.41 \pm 0.57) \times 10^{-3} h_{70}^3$ Mpc−3 dex−1. The sample was divided into low and high redshift bins to investigate the evolution of the HIMF. No change in low-mass slope α was measured, but an increased characteristic mass M*, was noted in the higher-redshift sample. Using Sloan Digital Sky Survey (SDSS) data to define relative galaxy number density, the dependence of the HIMF with environment was also investigated in the two AUDS regions. We find no significant variation in α or M*. In the surveyed region, we measured a cosmic HI density $\Omega _{\rm HI} = (3.55 \pm 0.30) \times 10^{-4} h_{70}^{-1}$. There appears to be no evolutionary trend in ΩHI above 2σ significance between redshifts of 0 and 0.16.

Primordial black holes from the QCD epoch: linking dark matter, baryogenesis, and anthropic selection

ABSTRACT If primordial black holes (PBHs) formed at the quark-hadron epoch, their mass must be close to the Chandrasekhar limit, this also being the characteristic mass of stars. If they provide the dark matter (DM), the collapse fraction must be of order the cosmological baryon-to-photon ratio ∼10−9, which suggests a scenario in which a baryon asymmetry is produced efficiently in the outgoing shock around each PBH and then propagates to the rest of the Universe. We suggest that the temperature increase in the shock provides the ingredients for hotspot electroweak baryogenesis. This also explains why baryons and DM have comparable densities, the precise ratio depending on the size of the PBH relative to the cosmological horizon at formation. The observed value of the collapse fraction and baryon asymmetry depends on the amplitude of the curvature fluctuations that generate the PBHs and may be explained by an anthropic selection effect associated with the existence of galaxies. We propose a scenario in which the quantum fluctuations of a light stochastic spectator field during inflation generate large curvature fluctuations in some regions, with the stochasticity of this field providing the basis for the required selection. Finally, we identify several observational predictions of our scenario that should be testable within the next few years. In particular, the PBH mass function could extend to sufficiently high masses to explain the black hole coalescences observed by LIGO/Virgo.

Improved Annotation of Untargeted Metabolomics Data Through Buffer Modifications That Shift Adduct Mass and Intensity

<p></p><p>Annotation of untargeted high-resolution full-scan LC-MS metabolomics data remains challenging due to individual metabolites generating multiple LC-MS peaks arising from isotopes, adducts and fragments. Adduct annotation is a particular challenge, as the same mass difference between peaks can arise from adduct formation, fragmentation, or different biological species. To address this, here we describe a Buffer Modification Workflow (BMW), in which the same sample is run by LC-MS in both liquid chromatography solvent with ¹⁴NH₃-acetate buffer, and in solvent with the buffer modified with ¹⁵NH₃-formate. Buffer switching results in characteristic mass and signal intensity changes for adduct peaks, facilitating their annotation. This relatively simple and convenient chromatography modification annotated yeast metabolomics data with similar effectiveness to growing the yeast in isotope-labeled media. Application to mouse liver data annotated both known metabolite and known adduct peaks with 95% accuracy. Overall, it identified 26% of ~ 27,000 liver LC-MS features as putative metabolites, of which ~ 2600 showed HMDB or KEGG database formula match. This workflow is well-suited to biological samples that cannot be readily isotope labeled, including plants, mammalian tissues, and tumors. </p><br><p></p>

Improved Annotation of Untargeted Metabolomics Data Through Buffer Modifications That Shift Adduct Mass and Intensity

<p></p><p>Annotation of untargeted high-resolution full-scan LC-MS metabolomics data remains challenging due to individual metabolites generating multiple LC-MS peaks arising from isotopes, adducts and fragments. Adduct annotation is a particular challenge, as the same mass difference between peaks can arise from adduct formation, fragmentation, or different biological species. To address this, here we describe a Buffer Modification Workflow (BMW), in which the same sample is run by LC-MS in both liquid chromatography solvent with ¹⁴NH₃-acetate buffer, and in solvent with the buffer modified with ¹⁵NH₃-formate. Buffer switching results in characteristic mass and signal intensity changes for adduct peaks, facilitating their annotation. This relatively simple and convenient chromatography modification annotated yeast metabolomics data with similar effectiveness to growing the yeast in isotope-labeled media. Application to mouse liver data annotated both known metabolite and known adduct peaks with 95% accuracy. Overall, it identified 26% of ~ 27,000 liver LC-MS features as putative metabolites, of which ~ 2600 showed HMDB or KEGG database formula match. This workflow is well-suited to biological samples that cannot be readily isotope labeled, including plants, mammalian tissues, and tumors. </p><br><p></p>

Improved Annotation of Untargeted Metabolomics Data Through Buffer Modifications That Shift Adduct Mass and Intensity

<p>Annotation of untargeted high-resolution full-scan LC-MS metabolomics data remains a difficult task. Existing literature suggests that LC-MS peaks can be divided into multiple major categories including “Background”, “Isotope”, “Adduct”, “Fragment” and “Candidate metabolite”. Among these, adduct annotation is a particular challenge, as the same mass difference between peaks can arise from adduct formation, fragmentation, or different biological species. To address this, here we describe a Buffer Modification Workflow (BMW), in which the same sample is run by LC-MS in both liquid chromatography solvent with ¹⁴NH₃-acetate buffer, and in solvent with the buffer modified with ¹⁵NH₃-formate. Buffer switching results in characteristic mass and signal intensity changes for adduct peaks, facilitating their annotation. In analyzing the candidate metabolite peaks, we recognized that some paradoxically increased in intensity over time between sample preparation and analysis. We show that such peaks are formed by chemical reactions between known metabolites and the extraction buffer and accordingly categorize these peaks as “Reaction Product”. Comparison using yeast extracts of BMW with a stable isotope labeling-based workflow suggests that BMW captures > 90% of candidate metabolites. This new workflow is well-suited to biological samples that cannot be readily isotope labeled, such as mammalian tissues and tumors. Application to mouse liver identified 26% of ~ 27,000 total peaks across positive and negative mode as candidate metabolites, of which ~ 2600 showed HMDB or KEGG database formula match.</p>

Aqueous-Phase Brown Carbon Formation from Aromatic Precursors under Sunlight Conditions

At present, there are still numerous unresolved questions concerning the mechanisms of light-absorbing organic aerosol (brown carbon, BrC) formation in the atmosphere. Moreover, there is growing evidence that chemical processes in the atmospheric aqueous phase can be important. In this work, we investigate the aqueous-phase formation of BrC from 3-methylcatechol (3MC) under simulated sunlight conditions. The influence of different HNO2/NO2− concentrations on the kinetics of 3MC degradation and BrC formation was investigated. Under illumination, the degradation of 3MC is faster (k2nd(global) = 0.075 M−1·s−1) in comparison to its degradation in the dark under the same solution conditions (k2nd = 0.032 M−1·s−1). On the other hand, the yield of the main two products of the dark reaction (3-methyl-5-nitrocatechol, 3M5NC, and 3-methyl-4-nitrocatechol, 3M4NC) is low, suggesting different degradation pathways of 3MC in the sunlight. Besides the known primary reaction products with distinct absorption at 350 nm, second-generation products responsible for the absorption above 400 nm (e.g., hydroxy-3-methyl-5-nitrocatechol, 3M5NC-OH, and the oxidative cleavage products of 3M4NC) were also confirmed in the reaction mixture. The characteristic mass absorption coefficient (MAC) values were found to increase with the increase of NO2−/3MC concentration ratio (at the concentration ratio of 50, MAC is greater than 4 m2·g−1 at 350 nm) and decrease with the increasing wavelength, which is characteristic for BrC. Yet, in the dark, roughly 50% more BrC is produced at comparable solution conditions (in terms of MAC values). Our findings reveal that the aqueous-phase processing of 3MC in the presence of HNO2/NO2−, both under the sunlight and in the dark, may significantly contribute to secondary organic aerosol (SOA) light absorption.

Development of reference materials with the composition of propyl and isopropyl alcohol solutions

Certified reference materials (CRM) composed of propyl (11383-2019) and isopropyl (11384-2019) alcohols solutions were created for validation of measurement procedures and control of measurement errors of measurement results of mass concentrations of toxic substances (alcohol) in biological objects (urine, blood) and water. Two ways of establishing the value of the certified characteristic – mass consentration of propanol-1 or propanol-2 have been studied. The results obtained by the preparation procedure and comparison with the standard are the same within the margin of error.

Axisymmetric Schwarzschild models of an isothermal axisymmetric mock dwarf spheroidal galaxy

Aims. The goal of this work is to test the ability of Schwarzschild’s orbit superposition method to measure the mass content, scale radius, and shape of a flattened dwarf spheroidal galaxy. Until now, most dynamical model efforts have assumed that dwarf spheroidal galaxies and their host halos are spherical. Methods. We used an Evans model (1993, MNRAS, 260, 191) to construct an isothermal mock galaxy whose properties somewhat resemble those of the Sculptor dwarf spheroidal galaxy. This mock galaxy contains flattened luminous and dark matter components, resulting in a logarithmic profile for the global potential. We tested whether the Schwarzschild method could constrain the characteristic parameters of the system for different sample sizes and whether this was possible without knowledge of the functional form of the potential. Results. When assuming the true functional form of the potential of the system, the Schwarzschild modelling technique is able to provide an accurate and precise measurement of the characteristic mass parameter of the system and accurately reproduces the light distribution and the stellar kinematics of our mock galaxy. When assuming a different functional form for the potential of the model, such as a flattened Navarro–Frenk–White (NFW) profile, we also constrain the mass and scale radius to their corresponding values. However in both cases, we find that the flattening parameter remains largely unconstrained. This is likely because the information content of the velocity dispersion on the geometric shape of the potential is too small. Conclusions. Our results using Schwarzschild’s method indicate that the mass enclosed can be derived reliably, even if the flattening parameter is unknown, and already for samples containing 2000 line-of-sight radial velocities, such as those currently available. Further applications of the method to more general distribution functions of flattened systems are needed to establish how well the flattening of dSph dark halos can be determined.