243 research outputs found
An easy synthesis for preparing bio-based hybrid adsorbent useful for fast adsorption of polar pollutants
For the first time, γ-Al2O3 and Bio-Based Substances (BBS) hybrids (A-BBS) were prepared through a simple electrostatic interaction occurring between alumina, used as a support, and BBS (Bio-Based Substance from composted biowastes) carrying positive and negative charges, respectively. We evaluated the optimal amount of BBS to be immobilized on the support and the stability of the resulting A-BBS in order to use this novel hybrid material as an adsorbent for the removal of polar pollutants. Characterization was carried out by X-Ray Diffraction (XRD) for evaluating the crystal structure of the support, Fourier transform infrared spectroscopy (FT-IR) to evidence the presence of BBS on the hybrid material, thermogravimetric analysis (TGA) to measure the thermal stability of the hybrid materials and quantify the BBS amount immobilized on the support, N2 adsorption at 77 K for the evaluation of the surface area and porosity of the systems, Zeta potential measurements to evaluate the effect of BBS immobilization on the surface charge of the particles and choose the substrates possibly interacting with them. Firstly, we tested the adsorption capability of three samples differently coated with BBS toward cationic species considering various adsorbate/adsorbent ratio. Crystal Violet (CV) was chosen as model pollutant to compare the performance of the hybrid materials with those of other materials described in the literature. The adsorption data were modeled by Langmuir and Freundlich adsorption isotherms. Then, we studied the adsorption capability of the developed material towards molecules with different structures; for this purpose, two contaminants of emerging concerns (carbamazepine and atenolol) were tested. The results indicate that A-BBS could be applied in wastewater treatment for the removal of a significant amount of polar species. In addition, a comparison with literature data concerning CV adsorption was carried out in order to evaluate the environmental impact of synthetic routes used to prepare different adsorbents
Observational Signatures of Frame Dragging in Strong Gravity
Objects orbiting in the presence of a rotating massive body experience a
gravitomagnetic frame-dragging effect, known as the Lense-Thirring effect, that
has been experimentally confirmed in the weak-field limit. In the strong-field
limit, near the horizon of a rotating black hole, frame dragging becomes so
extreme that all objects must co-rotate with the black hole's angular momentum.
In this work, we perform general relativistic numerical simulations to identify
observable signatures of frame dragging in the strong-field limit that appear
when infalling gas is forced to flip its direction of rotation as it is being
accreted. In total intensity images, infalling streams exhibit "S"-shaped
features due to the switch in the tangential velocity. In linear polarization,
a flip in the handedness of spatially resolved polarization ticks as a function
of radius encodes a transition in the magnetic field geometry that occurs due
to magnetic flux freezing in the dragged plasma. Using a network of telescopes
around the world, the Event Horizon Telescope collaboration has demonstrated
that it is now possible to directly image black holes on event horizon scales.
We show that the phenomena described in this work would be accessible to the
next-generation Event Horizon Telescope (ngEHT) and extensions of the array
into space, which would produce spatially resolved images on event horizon
scales with higher spatial resolution and dynamic range.Comment: Submitted to ApJL. 15 pages, 8 figure
How Spatially Resolved Polarimetry Informs Black Hole Accretion Flow Models
The Event Horizon Telescope (EHT) Collaboration has successfully produced
images of two supermassive black holes, enabling novel tests of black holes and
their accretion flows on horizon scales. The EHT has so far published total
intensity and linear polarization images, while upcoming images may include
circular polarization, rotation measure, and spectral index, each of which
reveals different aspects of the plasma and space-time. The next-generation EHT
(ngEHT) will greatly enhance these studies through wider recorded bandwidths
and additional stations, leading to greater signal-to-noise, orders of
magnitude improvement in dynamic range, multi-frequency observations, and
horizon-scale movies. In this paper, we review how each of these different
observables informs us about the underlying properties of the plasma and the
spacetime, and we discuss why polarimetric studies are well-suited to
measurements with sparse, long-baseline coverage.Comment: Submitted for Galaxies Special Issue "From Vision to Instrument:
Creating a Next-Generation Event Horizon Telescope for a New Era of Black
Hole Science
Association of depression and anxiety with clinical, sociodemographic, lifestyle and environmental factors in South Asian and white European people at high risk of diabetes
AIM: To investigate the prevalence and correlates of depressive and anxiety symptoms within South Asian and white European populations at high risk of developing Type 2 diabetes. METHODS: Data were collected at baseline, and at 12, 24 and 36 months from 1429 white European people (age 64±7 years, 35.8% women) and 160 South Asian people (age 59±9 years, 30.6% women) who were at high risk of Type 2 diabetes and who took part in two Type 2 diabetes prevention trials in Leicestershire, UK. The Hospital Anxiety and Depression Scale was administered during each study visit. Clinical, sociodemographic, lifestyle and environmental data were collected. RESULTS: At baseline, the burden of depressive symptoms varied by ethnic group and gender, with 9.9% of white European men, 14.9% of white European women, 23.6% of South Asian men and 29.2% of South Asian women exceeding the cut-off score for mild-to-severe depression. During the course of the study and after adjustment for clinical, sociodemographic, lifestyle and environmental factors, depressive symptoms remained higher in the South Asian compared to the white European participants [score higher by 1.5, 95% CI 0.9-2.1]. Levels of anxiety were also higher in the South Asian participants, although associations were attenuated after adjustment. Social deprivation, BMI, proximity to fast-food outlets and physical activity were correlates for depression in both the South Asian and white European participants. CONCLUSIONS: A higher burden of depressive symptoms was consistently evident among the South Asian participants, even after adjustment for multiple covariates. It is important to understand both the reasons why these differences are present, to help reduce health inequalities, and whether higher levels of depressive symptoms affect the uptake of and retention rates in diabetes prevention programmes in South Asian communities. This article is protected by copyright. All rights reserved
Anisotropic Inflation from Charged Scalar Fields
We consider models of inflation with U(1) gauge fields and charged scalar
fields including symmetry breaking potential, chaotic inflation and hybrid
inflation. We show that there exist attractor solutions where the anisotropies
produced during inflation becomes comparable to the slow-roll parameters. In
the models where the inflaton field is a charged scalar field the gauge field
becomes highly oscillatory at the end of inflation ending inflation quickly.
Furthermore, in charged hybrid inflation the onset of waterfall phase
transition at the end of inflation is affected significantly by the evolution
of the background gauge field. Rapid oscillations of the gauge field and its
coupling to inflaton can have interesting effects on preheating and
non-Gaussianities.Comment: minor changes, references added, figures are modified, conforms JCAP
published versio
The functional significance of aberrant cervical counts in sloths: insights from automated exhaustive analysis of cervical range of motion
Besides manatees, the suspensory extant ‘tree sloths’ are the only mammals that deviate from a cervical count (CC) of seven vertebrae. They do so in opposite directions in the two living genera (increased versus decreased CC). Aberrant CCs seemingly reflect neck mobility in both genera, suggesting adaptive significance for their head position during suspensory locomotion and especially increased ability for neck torsion in three-toed sloths. We test two hypotheses in a comparative evolutionary framework by assessing three-dimensional intervertebral range of motion (ROM) based on exhaustive automated detection of bone collisions and joint disarticulation while accounting for interacting rotations of roll, yaw and pitch. First, we hypothesize that the increase of CC also increases overall neck mobility compared with mammals with a regular CC, and vice versa. Second, we hypothesize that the anatomy of the intervertebral articulations determines mobility of the neck. The assessment revealed that CC plays only a secondary role in defining ROM since summed torsion (roll) capacity was primarily determined by vertebral anatomy. Our results thus suggest limited neck rotational adaptive significance of the CC aberration in sloths. Further, the study demonstrates the suitability of our automated approach for the comparative assessment of osteological ROM in vertebral series.Peer Reviewe
On the Robustness of the Velocity Anisotropy Parameter in Probing the Stellar Kinematics in Milky Way-Like Galaxies: Takeaway from TNG50 Simulation
We analyze the velocity anisotropy of stars in real and energy space for a sample of Milky Way-like galaxies in the TNG50 simulation. We employ different selection criteria, including spatial, kinematic, and metallicity cuts, and make three halo classes ( A-C) that show mild-to-strong sensitivity to different selections. The above classes cover 48%, 16%, and 36% of the halos, respectively. We analyze the beta radial profiles and divide them into either monotonically increasing radial profiles or ones with peaks and troughs. We demonstrate that halos with monotonically increasing beta profiles are mostly from class A , while those with peaks/troughs are part of classes B and C . This means that care must be taken, as the observationally reported peaks/troughs might be a consequence of different selection criteria. We infer the anisotropy parameter beta energy space and compare that against the beta radial profile. It is seen than 65% of halos with very mild sensitivity to different selections in real space are those for which the beta radial and energy profiles are closely related. Consequently, we propose that comparing the beta radial and energy profiles might be a novel way to examine the sensitivity to different selection criteria and thus examining the robustness of the anisotropy parameter in tracing stellar kinematics. We compare simulated beta radial profiles against various observations and demonstrate that, in most cases, the model diversity is comparable with the error bars from different observations, meaning that the TNG50 models are in good overall agreement with observations
COVID-19 vaccination uptake amongst ethnic minority communities in England: a linked study exploring the drivers of differential vaccination rates
BACKGROUND: Despite generally high coronavirus disease 2019 (COVID-19) vaccination rates in the UK, vaccination hesitancy and lower take-up rates have been reported in certain ethnic minority communities. METHODS: We used vaccination data from the National Immunisation Management System (NIMS) linked to the 2011 Census and individual health records for subjects aged ≥40 years (n = 24 094 186). We estimated age-standardized vaccination rates, stratified by ethnic group and key sociodemographic characteristics, such as religious affiliation, deprivation, educational attainment, geography, living conditions, country of birth, language skills and health status. To understand the association of ethnicity with lower vaccination rates, we conducted a logistic regression model adjusting for differences in geographic, sociodemographic and health characteristics. ResultsAll ethnic groups had lower age-standardized rates of vaccination compared with the white British population, whose vaccination rate of at least one dose was 94% (95% CI: 94%-94%). Black communities had the lowest rates, with 75% (74-75%) of black African and 66% (66-67%) of black Caribbean individuals having received at least one dose. The drivers of these lower rates were partly explained by accounting for sociodemographic differences. However, modelled estimates showed significant differences remained for all minority ethnic groups, compared with white British individuals. CONCLUSIONS: Lower COVID-19 vaccination rates are consistently observed amongst all ethnic minorities
Gas Morphology of Milky Way-like Galaxies in the TNG50 Simulation: Signals of Twisting and Stretching
We present an in-depth analysis of gas morphologies for a sample of 25 Milky
Way-like galaxies from the IllustrisTNG TNG50 simulation. We constrain the
morphology of cold, warm, hot gas, and gas particles as a whole using a Local
Shell Iterative Method (LSIM) and explore its observational implications by
computing the hard-to-soft X-ray ratio, which ranges between
- in the inner of the distribution and
- at the outer portion of the hot gas distribution. We group
galaxies into three main categories: simple, stretched, and twisted. These
categories are based on the radial reorientation of the principal axes of the
reduced inertia tensor. We find that a vast majority () of the galaxies
in our sample exhibit twisting patterns in their radial profiles. Additionally,
we present detailed comparisons between 1) the gaseous distributions belonging
to individual temperature regimes, 2) the cold gas distributions and stellar
distributions, and 3) the gaseous distributions and dark matter (DM) halos. We
find a strong correlation between the morphological properties of the cold gas
and stellar distributions. Furthermore, we find a correlation between gaseous
distributions with DM halo that increases with gas temperature, implying that
we may use the warm-hot gaseous morphology as a tracer to probe the DM
morphology. Finally, we show gaseous distributions exhibit significantly more
prolate morphologies than the stellar distributions and DM halos, which we
hypothesize is due to stellar and AGN feedback.Comment: 26 pages, 12 figure
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