327 research outputs found
Semiclassical Hartree-Fock theory of a rotating Bose-Einstein condensation
In this paper, we investigate the thermodynamic behavior of a rotating
Bose-Einstein condensation with non-zero interatomic interactions
theoretically. The analysis relies on a semiclassical Hartree-Fock
approximation where an integral is performed over the phase space and function
of the grand canonical ensemble is derived. Subsequently, we use this result to
derive several thermodynamic quantities including the condensate fraction,
critical temperature, entropy and heat capacity. Thereby, we investigate the
effect of the rotation rate and interactions parameter on the thermodynamic
behavior. The role of finite size is discussed. Our approach can be extended to
consider the rotating condensate in optical potential
A Literature Review on the Correlation Between Shear Bond Strength and the Degree of Conversion of Orthodontic Adhesive Systems
Objectives: The purpose of this study is to provide a comprehensive literature review on the correlation between shear bond strength and the degree of conversion of the orthodontic adhesive systems. Thus, this is considered as a major issue for the success of the orthodontic bonding techniques. Material and Methods: Electronic searches were performed in Pubmed and Scopus databases using relevant keywords. Textbook searching was also applied. Following the selection, full-text English language papers were fully reviewed to ensure that they met both the inclusion and the exclusion criteria. Results: Recent studies suggest that when increasing the DC, the SBS will increase. Thus, this results to a stiffer and a more durable resin. Conclusions: There is a wide range of factors affecting the SBS, DC, and their correlation. Some of them are related to the tooth etching techniques, adhesive related factors, curing units, and bracket materials. More research is required to develop more understanding of the role of these factors in determining the bonding success. This is because there are no specific published papers which were directly linked to the correlation between the SBS and the DC of orthodontic adhesives
Triage of the Gaia DR3 astrometric orbits. II. A census of white dwarfs
The third data release of Gaia was the first to include orbital solutions
assuming non-single stars. Here, we apply the astrometric triage technique of
Shahaf et al. to identify binary star systems with companions that are not
single main-sequence stars. Gaia's synthetic photometry of these binaries is
used to distinguish between systems likely to have white-dwarf companions and
those that may be hierarchical triples. The study uncovered a population of
nearly 3200 binaries, characterised by orbital separations on the order of an
astronomical unit, in which the faint astrometric companion is probably a white
dwarf. This sample increases the number of orbitally solved binary systems of
this type by about two orders of magnitude. Remarkably, over 110 of these
systems exhibit significant ultraviolet excess flux, confirming this
classification and, in some cases, indicating their relatively young cooling
ages. We show that the sample is not currently represented in synthetic binary
populations, and is not easily reproduced by available binary population
synthesis codes. Therefore, it challenges current binary evolution models,
offering a unique opportunity to gain insights into the processes governing
white-dwarf formation, binary evolution, and mass transfer.Comment: Accepted to MNRAS. See the arXiv submission files for the full tables
A1 and A
The origin of ultra diffuse galaxies: stellar feedback and quenching
We test if the cosmological zoom-in simulations of isolated galaxies from the
FIRE project reproduce the properties of ultra diffuse galaxies. We show that
stellar feedback-generated outflows that dynamically heat galactic stars,
together with a passively aging stellar population after imposed quenching
(from e.g. infall into a galaxy cluster), naturally reproduce the observed
population of red UDGs, without the need for high spin halos or dynamical
influence from their host cluster. We reproduce the range of surface
brightness, radius and absolute magnitude of the observed z=0 red UDGs by
quenching simulated galaxies at a range of different times. They represent a
mostly uniform population of dark matter-dominated galaxies with M_star ~1e8
Msun, low metallicity and a broad range of ages. The most massive simulated
UDGs require earliest quenching and are therefore the oldest. Our simulations
provide a good match to the central enclosed masses and the velocity
dispersions of the observed UDGs (20-50 km/s). The enclosed masses of the
simulated UDGs remain largely fixed across a broad range of quenching times
because the central regions of their dark matter halos complete their growth
early. A typical UDG forms in a dwarf halo mass range of Mh~4e10-1e11 Msun. The
most massive red UDG in our sample requires quenching at z~3 when its halo
reached Mh ~ 1e11 Msun. If it, instead, continues growing in the field, by z=0
its halo mass reaches > 5e11 Msun, comparable to the halo of an L* galaxy. If
our simulated dwarfs are not quenched, they evolve into bluer low-surface
brightness galaxies with mass-to-light ratios similar to observed field dwarfs.
While our simulation sample covers a limited range of formation histories and
halo masses, we predict that UDG is a common, and perhaps even dominant, galaxy
type around Ms~1e8 Msun, both in the field and in clusters.Comment: 20 pages, 13 figures; match the MNRAS accepted versio
Giardia intestinalis assemblages among Egyptian symptomatic/asymptomatic cases in Cairo
Giardia intestinalis is frequent enteric protozoa, affecting humans worldwide. Human infections aremainly caused by two genetically different assemblages call A & B. This cross-sectional study characterizedthe Giardia genotypes isolated from the stool of symptomatic and asymptomatic Egyptians inCairo and correlated these genotypes with the demographic and clinical data of the cases. Stool sampleswere collected from 389 individuals (245 complaining of gastrointestinal (GIT) symptoms and144 apparently healthy asymptomatic individuals), and microscopically examined. Positive Samplesfor G. intestinalis were molecularly characterized by Copro-nPCR targeting beta-giardin gene, andthen analyzed by RFLP for assemblage identification. Giardia was detected in 62 samples (15.9%); 53samples in symptomatic cases (21.6%) and 9 samples in asymptomatic individuals (6.25%). DNA ofpositive samples was amplified by nPCR-RFLP assays. There was a significant predominance of assemblageB among symptomatic (82.7%) and asymptomatic (77.8%) groups, while the rest of sampleshad assemblage A. Among the clinical data, only flatulence was significantly associated with Giardiainfection with assemblage B. Assemblage B is the predominant genotype found in Egypt in symptomaticand asymptomatic patients suggesting an anthropologic transmission cycle.Key Words: Giardia; genotyping; Assemblage; nPCR-RFLP; beta-giardin
A profile in FIRE: resolving the radial distributions of satellite galaxies in the Local Group with simulations
While many tensions between Local Group (LG) satellite galaxies and LCDM
cosmology have been alleviated through recent cosmological simulations, the
spatial distribution of satellites remains an important test of physical models
and physical versus numerical disruption in simulations. Using the FIRE-2
cosmological zoom-in baryonic simulations, we examine the radial distributions
of satellites with Mstar > 10^5 Msun around 8 isolated Milky Way- (MW) mass
host galaxies and 4 hosts in LG-like pairs. We demonstrate that these
simulations resolve the survival and physical destruction of satellites with
Mstar >~ 10^5 Msun. The simulations broadly agree with LG observations,
spanning the radial profiles around the MW and M31. This agreement does not
depend strongly on satellite mass, even at distances <~ 100 kpc. Host-to-host
variation dominates the scatter in satellite counts within 300 kpc of the
hosts, while time variation dominates scatter within 50 kpc. More massive host
galaxies within our sample have fewer satellites at small distances, likely
because of enhanced tidal destruction of satellites via the baryonic disks of
host galaxies. Furthermore, we quantify and provide fits to the tidal depletion
of subhalos in baryonic relative to dark matter-only simulations as a function
of distance. Our simulated profiles imply observational incompleteness in the
LG even at Mstar >~ 10^5 Msun: we predict 2-10 such satellites to be discovered
around the MW and possibly 6-9 around M31. To provide cosmological context, we
compare our results with the radial profiles of satellites around MW analogs in
the SAGA survey, finding that our simulations are broadly consistent with most
SAGA systems.Comment: 18 pages, 10 figures, plus appendices. Main results in figures 2, 3,
and 4. Accepted versio
Star formation histories of dwarf galaxies in the FIRE simulations: dependence on mass and Local Group environment
We study star formation histories (SFHs) of dwarf galaxies
(stellar mass ) from FIRE-2 cosmological zoom-in
simulations. We compare dwarfs around individual Milky Way (MW)-mass galaxies,
dwarfs in Local Group (LG)-like environments, and true field (i.e. isolated)
dwarf galaxies. We reproduce observed trends wherein higher-mass dwarfs quench
later (if at all), regardless of environment. We also identify differences
between the environments, both in terms of "satellite vs. central" and "LG vs.
individual MWvs. isolated dwarf central." Around the individual MW-mass hosts,
we recover the result expected from environmental quenching: central galaxies
in the "near field" have more extended SFHs than their satellite counterparts,
with the former more closely resemble isolated ("true field") dwarfs (though
near-field centrals are still somewhat earlier forming). However, this
difference is muted in the LG-like environments, where both near-field centrals
and satellites have similar SFHs, which resemble satellites of single MW-mass
hosts. This distinction is strongest for but
exists at other masses. Our results suggest that the paired halo nature of the
LG may regulate star formation in dwarf galaxies even beyond the virial radii
of the MW and Andromeda. Caution is needed when comparing zoom-in simulations
targeting isolated dwarf galaxies against observed dwarf galaxies in the LG.Comment: Main text: 11 pages, 8 figures; appendices: 4 pages, 4 figures.
Submitted to MNRAS; comments welcom
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