Primordial gas in protogalactic DM halos with virial temperatures image begins to cool and condense via atomic hydrogen. Provided that this gas is irradiated by a strong UV flux and remains free of H ...sub(2) and other molecules, it has been proposed that the halo with image may avoid fragmentation and lead to the rapid formation of an SMBH as massive as image. This 'head start' would help explain the presence of SMBHs with inferred masses of several times 10 super(9) M sub(image), powering the bright quasars discovered in the SDSS at redshift image. However, high- redshift DM halos with image are likely already enriched with at least trace amounts of metals and dust produced by prior star formation in their progenitors. Here we study the thermal and chemical evolution of low- metallicity gas exposed to extremely strong UV radiation fields. Our results, obtained in one-zone models, suggest that gas fragmentation is inevitable above a critical metallicity, whose value is between image (in the absence of dust) and as low as image (with a dust-to-gas mass ratio of about image). We propose that when the metallicity exceeds these critical values, dense clusters of low-mass stars may form at the halo nucleus. Relatively massive stars in such a cluster can then rapidly coalesce into a single more massive object, which may produce an intermediate-mass BH remnant with a mass up to image.
The use of poultry litter as a biological soil amendment presents a risk for the preharvest contamination of fresh produce by Salmonella. In order to properly assess this risk, it is important to ...understand the factors influencing the persistence of Salmonella in poultry litter. This research was performed to investigate the influence of indigenous microflora on the survival of Salmonella Typhimurium in poultry litter. Microcosms of irradiated (sterilized) and natural poultry litter were inoculated with S. Typhimurium, adjusted to pH 8.0, 0.92 water activity (aw), and stored at 30°C for 6 days. S. Typhimurium populations (log CFU g-1) declined in both litter treatments and there were no significant differences (P > 0.05) in recovery between litter treatments on any sampling days (0 to 6). The pH of the natural litter significantly increased (P < 0.05) from 8.42 on day 0 to 9.00 on day 6. By day 6, S. Typhimurium populations in both litter treatments fell below the limit of detection (1 log CFU g-1). The inactivation kinetics of S. Typhimurium in both litter treatments were described by the Weibull model. Under the experimental conditions (pH 8.0, 0.92 aw, 30°C), the presence or absence of poultry litter microflora did not significantly influence the survival of S. Typhimurium. This study demonstrates that the mere presence of poultry litter microflora will not inhibit Salmonella survival. Instead, inhibitory interactions between various microorganisms in litter and Salmonella are likely dependent on more favorable environmental conditions (e.g., aw, pH) for growth and competition.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Single-cell RNA sequencing (scRNA-seq) has been widely applied to dissect cellular heterogeneity in normal and diseased skin. Sebaceous glands, essential skin components with established functions in ...maintaining skin integrity and emerging roles in systemic energy metabolism, have been largely neglected in scRNA-seq studies.
Departing from mouse and human skin scRNA-seq datasets, we identified gene sets expressed especially in sebaceous glands with the open-source R-package oposSOM.
The identified gene sets included sebaceous gland-typical genes as Scd3, Mgst1, Cidea, Awat2 and KRT7. Surprisingly, however, there was not a single overlap among the 100 highest, exclusively in sebaceous glands expressed transcripts in mouse and human samples. Notably, both species share a common core of only 25 transcripts, including mitochondrial and peroxisomal genes involved in fatty acid, amino acid, and glucose processing, thus highlighting the intense metabolic rate of this gland.
This study highlights intrinsic differences in sebaceous lipid synthesis between mice and humans, and indicates an important role for peroxisomal processes in this context. Our data also provides attractive starting points for experimentally addressing novel candidates regulating sebaceous gland homeostasis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT
We investigate the impact of strong initial magnetic fields in core-collapse supernovae of non-rotating progenitors by simulating the collapse and explosion of a $16.9\, \mathrm{M}_\odot$ ...star for a strong- and weak-field case assuming a twisted-torus field with initial central field strengths of ${\approx }10^{12}$ and ${\approx }10^{6}\, \mathrm{G}$. The strong-field model has been set up with a view to the fossil-field scenario for magnetar formation and emulates a pre-collapse field configuration that may occur in massive stars formed by a merger. This model undergoes shock revival already $100\, \mathrm{ms}$ after bounce and reaches an explosion energy of $9.3\times 10^{50}\, \mathrm{erg}$ at $310\, \mathrm{ms}$, in contrast to a more delayed and less energetic explosion in the weak-field model. The strong magnetic fields help trigger a neutrino-driven explosion early on, which results in a rapid rise and saturation of the explosion energy. Dynamically, the strong initial field leads to a fast build-up of magnetic fields in the gain region to 40 per cent of kinetic equipartition and also creates sizable pre-shock ram pressure perturbations that are known to be conducive to asymmetric shock expansion. For the strong-field model, we find an extrapolated neutron star kick of ${\approx }350\, \mathrm{km}\, \mathrm{s}^{-1}$, a spin period of ${\approx }70\, \mathrm{ms}$, and no spin-kick alignment. The dipole field strength of the proto-neutron star is $2\times 10^{14}\, \mathrm{G}$ by the end of the simulation with a declining trend. Surprisingly, the surface dipole field in the weak-field model is stronger, which argues against a straightforward connection between pre-collapse fields and the birth magnetic fields of neutron stars.
We study the impact of star-forming minihaloes, and the initial mass function (IMF) of Population III (Pop III) stars, on the Galactic halo metallicity distribution function (MDF) and on the ...properties of C-enhanced and C-normal stars at Fe/H < -3. For our investigation we use a data-constrained merger tree model for the Milky Way formation, which has been improved to self-consistently describe the physical processes regulating star formation in minihaloes, including the poor sampling of the Pop III IMF. We find that only when star-forming minihaloes are included the low-Fe tail of the MDF is correctly reproduced, showing a plateau that is built up by C-enhanced metal-poor stars imprinted by primordial faint supernovae. The incomplete sampling of the Pop III IMF in inefficiently star-forming minihaloes (<10 super( -3) M... yr super( -1)) strongly limits the formation of pair-instability supernovae (PISNe), with progenitor masses mPopIII = 140-260 M..., even when a flat Pop III IMF is assumed. Second-generation stars formed in environments polluted at >50 per cent level by PISNe are thus extremely rare, corresponding to ...0.25 per cent of the total stellar population at Fe/H < -2, which is consistent with recent observations. The low-Fe tail of the MDF strongly depends on the Pop III IMF shape and mass range. Given the current statistics, we find that a flat Pop III IMF model with mPopIII = 10-300 M... is disfavoured by observations. We present testable predictions for Pop III stars extending down to lower masses, with mPopIII = 0.1-300 M... (ProQuest: ... denotes formulae/symbols omitted.)
For polyhedral convex cones in
R
d
, we give a proof for the conic kinematic formula for conic curvature measures, which avoids the use of characterization theorems. For the random cones defined as ...typical cones of an isotropic random central hyperplane arrangement, we find probabilities for non-trivial intersection, either with a fixed cone, or for two independent random cones of this type.
Objective
This narrative review examines six important non‐nutritive substances in breast milk, many of which were thought to have little to no biological significance. The overall objective is to ...provide background on key bioactive factors in breast milk believed to have an effect on infant outcomes (growth and body composition).
Methods
The evidence for the effects of the following six bioactive compounds in breast milk on infant growth outcomes are reviewed: insulin, leptin, adiponectin, ghrelin, interleukin‐6, and tumor necrosis factor‐α.
Results
The existing literature on the effects of breast milk insulin, ghrelin, interleukin‐6, and tumor necrosis factor‐α and their associations with infant growth and adiposity is sparse. Of the bioactive compounds reviewed, leptin and adiponectin are the most researched. Data reveal that breast milk adiponectin has negative associations with growth in infancy.
Conclusions
There is a need for innovative, well‐designed studies to improve causal inference and advance our understanding in the effects of breast milk and its components on offspring growth and body composition. The recommendations provided, along with careful consideration of both known and unknown factors that affect breast milk composition, will help improve, standardize, and ultimately advance this emergent field.
The transition into college can pose barriers for student success. We examined the impact of mindfulness-based stress reduction (MBSR) compared to an active and no treatment control group, ...respectively, on stressor appraisals, academic persistence, and performance in unversity students.
Students were randomly assigned to receive MBSR (n = 29), study skills active control (n = 27), or no treatment (n = 29).
Participants reported stressor appraisals and academic persistence pre- and post-intervention. Semester grade point average (GPA) and enrollment was also obtained.
Academic stressor appraisals did not vary by group. MBSR was protective against depleted academic persistence, whereas academic persistence decreased in the control groups. Enrollment rates remained unchanged in the MBSR group, but increased in the active control relative to no treatment. Finally, GPA improved in the MBSR group, but not controls.
Findings suggest that MBSR confers some benefits for resilience in university students.
The epidermal growth factor receptor (EGFR) and a coreceptor denoted HER2/ERBB2 are frequently overexpressed or mutated in solid tumors, such as carcinomas and gliomas. In line with driver roles, ...cancer drugs intercepting EGFR or HER2 currently outnumber therapies targeting other hubs of signal transduction. To explain the roles for EGFR and HER2 as prime drivers and targets, we take lessons from invertebrates and refer to homeostatic regulation of several mammalian tissues. The model we infer ascribes to the EGFR-HER2 module pivotal functions in rapid clonal expansion of progenitors called transient amplifying cells (TACs). Accordingly, TACs of tumors suffer from replication stress, and hence accumulate mutations. In addition, several lines of evidence propose that in response to EGF and related mitogens, TACs might undergo dedifferentiation into tissue stem cells, which might enable entry of oncogenic mutations into the stem cell compartment. According to this view, antibodies or kinase inhibitors targeting EGFR-HER2 effectively retard some solid tumors because they arrest mutation-enriched TACs and possibly inhibit their dedifferentiation. Deeper understanding of the EGFR-HER2 module and relations between cancer stem cells and TACs will enhance our ability to control a broad spectrum of human malignancies.
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