Abstract
Pepper mild mottle virus (PMMoV) was recently found to be the most abundant RNA virus in human feces, and is a plant virus belonging to the genus
Tobamovirus
in the family
Virgoviridae
. ...When in human feces, it is of dietary origin from peppers and their processed products, and is excreted from a large proportion of healthy human populations, but rarely found in animal feces. Over the past decade, this virus has been increasingly attracting research attention as a potential viral indicator for human fecal pollution in aquatic environments and water treatment systems. Results presented in the literature reveal that PMMoV is globally distributed and present in various water sources in greater abundance than human pathogenic viruses, without substantial seasonal fluctuations. Several studies report that increased concentrations of PMMoV tend to be correlated with increased fecal contamination in general, along with more frequent detection of pathogenic enteric viruses. PMMoV also exhibits remarkable stability in water under various environmental conditions. Here, we review recent advancements in our understanding of the occurrence and persistence of PMMoV in natural and engineered water systems and discuss its advantages and limitations as a viral indicator for improved microbial water quality management.
Abstract
The distribution of elements in galaxies provides a wealth of information about their production sites and their subsequent mixing into the interstellar medium. Here we investigate the ...elemental distributions of stars in the IllustrisTNG simulations. We analyse the abundance ratios of magnesium and europium in Milky Way-like galaxies from the TNG100 simulation (stellar masses log (M⋆/M⊙) ∼ 9.7–11.2). Comparison of observed magnesium and europium for individual stars in the Milky Way with the stellar abundances in our more than 850 Milky Way-like galaxies provides stringent constraints on our chemical evolutionary methods. Here, we use the magnesium-to-iron ratio as a proxy for the effects of our SNII (core-collapse supernovae) and SNIa (Type Ia supernovae) metal return prescription and as a comparison to a variety of galactic observations. The europium-to-iron ratio tracks the rare ejecta from neutron star–neutron star mergers, the assumed primary site of europium production in our models, and is a sensitive probe of the effects of metal diffusion within the gas in our simulations. We find that europium abundances in Milky Way-like galaxies show no correlation with assembly history, present-day galactic properties, and average galactic stellar population age. We reproduce the europium-to-iron spread at low metallicities observed in the Milky Way, and find it is sensitive to gas properties during redshifts z ≈ 2–4. We show that while the overall normalization of Eu/Fe is susceptible to resolution and post-processing assumptions, the relatively large spread of Eu/Fe at low Fe/H when compared to that at high Fe/H is quite robust.
Abstract
The IllustrisTNG project is a new suite of cosmological magnetohydrodynamical simulations of galaxy formation performed with the arepo code and updated models for feedback physics. Here, we ...introduce the first two simulations of the series, TNG100 and TNG300, and quantify the stellar mass content of about 4000 massive galaxy groups and clusters (1013 ≤ M200c/M⊙ ≤ 1015) at recent times (z ≤ 1). The richest clusters have half of their total stellar mass bound to satellite galaxies, with the other half being associated with the central galaxy and the diffuse intracluster light. Haloes more massive than about 5 × 1014 M⊙ have more diffuse stellar mass outside 100 kpc than within 100 kpc, with power-law slopes of the radial mass density distribution as shallow as the dark matter's ( − 3.5 ≲ α3D ≲ −3). Total halo mass is a very good predictor of stellar mass, and vice versa: at z = 0, the 3D stellar mass measured within 30 kpc scales as ∝(M500c)0.49 with a ∼0.12 dex scatter. This is possibly too steep in comparison to the available observational constraints, even though the abundance of The Next Generation less-massive galaxies ( ≲ 1011 M⊙ in stars) is in good agreement with the measured galaxy stellar mass functions at recent epochs. The 3D sizes of massive galaxies fall too on a tight (∼0.16 dex scatter) power-law relation with halo mass, with $r^{\rm stars}_{\rm 0.5} \propto (M_{\rm 200c})^{0.53}$. Even more fundamentally, halo mass alone is a good predictor for the whole stellar mass profiles beyond the inner few kiloparsecs, and we show how on average these can be precisely recovered given a single-mass measurement of the galaxy or its halo.
With increasing pressure to understand transmissible agents, renewed recognition of infectious causation of both acute and chronic diseases is occurring. Epidemiological and neuropathological studies ...indicate that some cases of schizophrenia may be associated with environmental factors, such as exposure to the ubiquitous protozoan Toxoplasma gondii. Reasons for this include T. gondii's ability to establish persistent infection within the central nervous system, its ability to manipulate intermediate host behaviour, the occurrence of neurological and psychiatric symptoms in some infected individuals, and an association between infection with increased incidence of schizophrenia. Moreover, several of the medications used to treat schizophrenia and other psychiatric disease have recently been demonstrated in vitro to possess anti-parasitic, and in particular anti-T. gondii, properties. Our aim here was thus to test the hypothesis that the anti-psychotic and mood stabilizing activity of some medications may be achieved, or at least augmented, through their in vivo inhibition of T. gondii replication and invasion in infected individuals. In particular we predicted, using the epidemiologically and clinically applicable rat-T. gondii model system, and following a previously described and neurologically characterized 'feline attraction' protocol that haloperidol (an anti-psychotic used in the treatment of mental illnesses including schizophrenia) and/or valproic acid (a mood stabilizer used in the treatment of mental illnesses including schizophrenia), would be, at least, as effective in preventing the development of T. gondii-associated behavioural and cognitive alterations as the standard anti-T. gondii chemotherapeutics pyrimethamine with Dapsone. We demonstrate that, while T. gondii appears to alter the rats' perception of predation risk turning their innate aversion into a 'suicidal' feline attraction, anti-psychotic drugs prove as efficient as anti-T. gondii drugs in preventing such behavioural alterations. Our results have important implications regarding the aetiology and treatment of such disorders.
Harmful and nuisance algal blooms are becoming a greater concern to public health, riverine ecosystems, and recreational uses of inland waterways. Algal bloom proliferation has increased in the Upper ...Clark Fork River due to a combination of warming water temperatures, naturally high phosphorus levels, and an influx of nitrogen from various sources. To improve understanding of bloom dynamics and how they affect water quality, often measured as algal biomass measured through pigment standing crops, a UAV-based hyperspectral imaging system was deployed to monitor several locations along the Upper Clark Fork River in western Montana. Image data were collected across the spectral range of 400–1000 nm with 2.1 nm spectral resolution during two field sampling campaigns in 2021. Included are methods to estimate chl a and phycocyanin standing crops using regression analysis of salient wavelength bands, before and after separating the pigments according to their growth form. Estimates of chl a and phycocyanin standing crops generated through a linear regression analysis are compared to in situ data, resulting in a maximum R2 of 0.96 for estimating fila/epip chl-a and 0.94 when estimating epiphytic phycocyanin. Estimates of pigment standing crops from total abundance, epiphytic, and the sum of filamentous and epiphytic sources are also included, resulting in a promising method for remotely estimating algal standing crops. This method addresses the shortcomings of current monitoring techniques, which are limited in spatial and temporal scale, by proposing a method for rapid collection of high-spatial-resolution pigment abundance estimates.
The growth activity of Bact. abortus is governed by an increased carbon dioxide tension, by the liberation of hydrogen sulphide and the formation of ammonium magnesium phosphate; the production of ...the latter two substances being controlled by an abundance of carbon dioxide and the reaction of the culture medium. It is pointed out that there is a biochemical reaction which serves to distinguish Bact. abortus from Br. melitensis, that is, in the formation of ammonium magnesium phosphate and liberation of hydrogen sulphide. Bact. abortus may be measured quantitatively in infective milk with a high degree of accuracy by employing, as a culture medium, gentian violet, beef liver infusion agar, and incubating in an atmosphere containing from 5 to 10% carbon dioxide. In the gravity separation of cream the rising fat globules and body cells carry with them the majority of the abortion bacteria in milk. The culturing of the gravity cream layer of milk is just as efficient for determining the presence of Bact. abortus in milk as are guinea-pig inoculation methods. Bact. abortus does not appear to multiply in milk held at ice box temperatures and decreases in numbers rapidly when held longer than eight days. The number of colonies of Bact. abortus which develop on plated culture medium, decreases as the length of time they are held aerobically at 37 C. increases.
Teaching for Learning Torrey, Rubye P
Journal of Chemical Education,
1976, Letnik:
53, Številka:
1
Journal Article
Describes an undergraduate analytical chemistry course that utilizes instrument modules, which show how the key parts of an instrument fit together and contribute to the overall operation of the ...instrument. (MLH)
Large-scale cosmological simulations of galaxy formation currently do not resolve the densities at which molecular hydrogen forms, implying that the atomic-to-molecular transition must be modeled ...either on the fly or in postprocessing. We present an improved postprocessing framework to estimate the abundance of atomic and molecular hydrogen and apply it to the IllustrisTNG simulations. We compare five different models for the atomic-to-molecular transition, including empirical, simulation-based, and theoretical prescriptions. Most of these models rely on the surface density of neutral hydrogen and the ultraviolet (UV) flux in the Lyman-Werner band as input parameters. Computing these quantities on the kiloparsec scale resolved by the simulations emerges as the main challenge. We show that the commonly used Jeans length approximation to the column density of a system can be biased and exhibits large cell-to-cell scatter. Instead, we propose to compute all surface quantities in face-on projections and perform the modeling in two dimensions. In general, the two methods agree on average, but their predictions diverge for individual galaxies and for models based on the observed midplane pressure of galaxies. We model the UV radiation from young stars by assuming a constant escape fraction and optically thin propagation throughout the galaxy. With these improvements, we find that the five models for the atomic-to-molecular transition roughly agree on average but that the details of the modeling matter for individual galaxies and the spatial distribution of molecular hydrogen. We emphasize that the estimated molecular fractions are approximate due to the significant systematic uncertainties.
PDF
