351 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
Synthesis of Dynamic 2-Ethoxycarbonyl-4H-3, 1-Benzoxazin-4-one and its Behavior Towards Nitrogen Nucleophiles
The behavior of 2-ethoxycarbonyl-4H-3,1-benzoxazin-4-one and its behavior towards nitrogen nucleophiles namely, hydrazine hydrate, formamide, benzylamine, ethylamine, piperidine, ethanol amine, o-phenylenediamine, and glucosamine hydrochloride has been investigated. Also the reaction of 3-[aminoquinazolin-4(3H)-one-2-yl]formic acid hydrazide with aromatic aldehydes and phenylisothiocyanate has been discussed. The structure of the prepared compounds are elucidated using physical and spectral data like, FT-IR, 1HNMR, and mass spectroscopy
AGN All the Way Down? AGN-like Line Ratios are Common In the Lowest-Mass Isolated Quiescent Galaxies
We investigate the lowest-mass quiescent galaxies known to exist in isolated
environments (; 1.5 Mpc from a more
massive galaxy). This population may represent the lowest stellar mass galaxies
in which internal feedback quenches galaxy-wide star formation. We present
Keck/ESI long-slit spectroscopy for 27 isolated galaxies in this regime: 20
quiescent galaxies and 7 star-forming galaxies. We measure emission line
strengths as a function of radius and place galaxies on the Baldwin Phillips
Terlevich (BPT) diagram. Remarkably, 16 of 20 quiescent galaxies in our sample
host central AGN-like line ratios. Only 5 of these quiescent galaxies were
identified as AGN-like in SDSS due to lower spatial resolution and
signal-to-noise. We find that many of the quiescent galaxies in our sample have
spatially-extended emission across the non-SF regions of BPT-space. When
considering only the central 1, we identify a tight
relationship between distance from the BPT star-forming sequence and host
galaxy stellar age as traced by , such that older stellar
ages are associated with larger distances from the star-forming locus. Our
results suggest that the presence of hard ionizing radiation (AGN-like line
ratios) is intrinsically tied to the quenching of what may be the lowest-mass
self-quenched galaxies.Comment: 16 pages, 9 figures, submitted to Ap
COVID-19 Detection on Chest x-ray Images by Combining Histogram-oriented Gradient and Convolutional Neural Network Features
The COVID-19 coronavirus epidemic has spread rapidly worldwide after a person became infected with a severe health problem. The World Health Organization has declared the coronavirus a global threat (WHO). Early detection of COVID 19, particularly in cases with no apparent symptoms, may reduce the patients mortality rate. COVID 19 detection using machine learning techniques will aid healthcare systems around the world in recovering patients more rapidly. This disease is diagnosed using x-ray images of the chest; therefore, this study proposed a machine vision method for detecting COVID-19 in x-ray images of the chest. The histogram-oriented gradient (HOG) and convolutional neural network (CNN) features extracted from x-ray images were fused and classified using support vector machine (SVM) and softmax. The proposed feature fusion technique (99.36 percent) outperformed individual feature extraction methods such as HOG (87.34 percent) and CNN (93.64 percent)
Dark and luminous satellites of LMC-mass galaxies in the FIRE simulations
Within lambda cold dark matter (CDM), dwarf galaxies like the Large Magellanic Cloud (LMC) are expected to host numerous dark matter subhaloes, several of which should host faint dwarf companions. Recent Gaia proper motions confirm new members of the LMC system in addition to the previously known SMC, including two classical dwarf galaxies (M∗ > 105 M; Carina and Fornax) as well as several ultrafaint dwarfs (Car2, Car3, Hor1, and Hyd1). We use the Feedback In Realistic Environments (FIRE) simulations to study the dark and luminous (down to ultrafaint masses, M∗ ∼6×103 M) substructure population of isolated LMC-mass hosts (M200m = 1–3×1011 M) and place the Gaia + DES results in a cosmological context. By comparing number counts of subhaloes in simulations with and without baryons, we find that, within 0.2 r200m, LMC-mass hosts deplete ∼30 per cent of their substructure, significantly lower than the ∼70 per cent of substructure depleted by Milky Way (MW) mass hosts. For our highest resolution runs (mbary = 880 M), ∼ 5–10 subhaloes form galaxies with M∗ ≥ 104 M , in agreement with the seven observationally inferred pre-infall LMC companions. However, we find steeper simulated luminosity functions than observed, hinting at observation incompleteness at the faint end. The predicted DM content for classical satellites in FIRE agrees with observed estimates for Carina and Fornax, supporting the case for an LMC association. We predict that tidal stripping within the LMC potential lowers the inner dark matter density of ultrafaint companions of the LMC. Thus, in addition to their orbital consistency, the low densities of dwarfs Car2, Hyd1, and Hyd2 reinforce their likelihood of Magellanic association
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