scholarly journals Asymmetric drift of Andromeda analogues in the IllustrisTNG simulation

2020 ◽  
Vol 497 (3) ◽  
pp. 2870-2882
Author(s):  
Amanda C N Quirk ◽  
Ekta Patel
Keyword(s):  
High Resolution ◽  
Rotation Curve ◽  
Age Groups ◽  
Time Frame ◽  
Centre Of Mass ◽  
Stellar Rotation ◽  
Internal Heating ◽  
Rotation Curves ◽  
Neutral Gas ◽  
Andromeda Galaxy

ABSTRACT We analyse the kinematics as a function of stellar age for Andromeda (M31) mass analogues from the IllustrisTNG cosmological simulation. We divide the star particles into four age groups: <1, 1–5, 5–10, and >10 Gyr, and compare the kinematics of these groups to that of the neutral gas cells. We calculate rotation curves for the stellar and gaseous components of each analogue from 2 to 20 kpc from the centre of mass. We find that the lag, or asymmetric drift (AD), between the gas rotation curve and the stellar rotation curve on average increases with stellar age. This finding is consistent with observational measurements of AD in the disc of the Andromeda galaxy. When the M31 analogues are separated into groups based on merger history, we find that there is a difference in the AD of the analogues that have had a 4:1 merger the last 4, 8, or 12 Gyr compared to analogues that have not experienced a 4:1 merger in the same time frame. The subset of analogues that have had a 4:1 merger within the last 4 Gyr are also similar to AD measurements of stars in M31’s disc, providing evidence that M31 may in fact have recently merged with a galaxy nearly one-fourth of its mass. Further work using high-resolution zoom-in simulations is required to explore the contribution of internal heating to AD.

scholarly journals HI and Hα Mapping of M31 & M33

2010 ◽  
Vol 6 (S277) ◽  
pp. 116-120
Author(s):  
Z. S. Kam ◽  
C. Carignan ◽  
L. Chemin ◽  
O. Hernandez ◽  
M. de Denus-Baillargeon ◽  
...  
Keyword(s):  
High Resolution ◽  
Rotation Curve ◽  
Local Group ◽  
Low Resolution ◽  
Rotation Curves ◽  
Fabry Perot ◽  
Central Regions ◽  
Kinematical Parameters ◽  
Kinematical Data

RésuméWe performed a deep Hi and Hα mapping of M31 and M33 in order to get accurate kinematical data of those two galaxies and also to make a comparison between the Hi and Hα kinematics. The Hi data were obtained with the DRAO interferometer and the Hα data with the Fabry-Perot system of the Observatoire du mont Mégantic using an EMCCD as a detector. These data will give us the best possible datasets to derive accurate rotation curves and mass models for those two Local Group spirals and provide some new data for the Hii regions studies of these galaxies. While the Hi observations are of low resolution (~1 arcmin), the high resolution of the Hα data (~1 arcsec) should allow us to get much more details in the central regions, allowing at the same time a much better determination of the kinematical parameters. Hence, the inner part of the rotation curve, so inportant to constraint properly the mass models, will be determined more accurately.

scholarly journals Comparison of Global 21 cm Velocity Profiles with Hα Rotation Curves

1983 ◽  
Vol 100 ◽  
pp. 29-30
Author(s):  
Norbert Thonnard
Keyword(s):  
High Resolution ◽  
Velocity Gradient ◽  
Rotation Curve ◽  
Optical Rotation ◽  
Velocity Profiles ◽  
Rotation Curves ◽  
Peak Intensity

21 cm profiles are compared with high resolution long slit Hα spectra. Asymmetries in intensity and velocity gradient in the spectra are apparent in the global profiles. When measured at 0.5 of peak intensity, the 21cm profile width and optical rotation curve match best.

scholarly journals Exploring the robustness of Keplerian signals to the removal of active and telluric features

2020 ◽  
Vol 500 (1) ◽  
pp. 548-557
Author(s):  
M Lisogorskyi ◽  
H R A Jones ◽  
F Feng ◽  
R P Butler ◽  
S Vogt
Keyword(s):  
Monte Carlo ◽  
High Resolution ◽  
Monte Carlo Simulations ◽  
Large Amplitude ◽  
Absorption Cell ◽  
Stellar Rotation ◽  
Long Period ◽  
Active Line ◽  
Low Amplitude ◽  
Rotation Signal

ABSTRACT We examine the influence of activity- and telluric-induced radial velocity (RV) signals on high-resolution spectra taken with an iodine absorption cell. We exclude 2-$\mathring{\rm A}$ spectral chunks containing active and telluric lines based on the well-characterized K1V star α Centauri B and illustrate the method on Epsilon Eridani – an active K2V star with a long-period, low-amplitude planetary signal. After removal of the activity- and telluric-sensitive parts of the spectrum from the RV calculation, the significance of the planetary signal is increased and the stellar rotation signal disappears. In order to assess the robustness of the procedure, we perform Monte Carlo simulations based on removing random chunks of the spectrum. Simulations confirm that the removal of lines impacted by activity and tellurics provides a method for checking the robustness of a given Keplerian signal. We also test the approach on HD 40979, which is an active F8V star with a large-amplitude planetary signal. Our Monte Carlo simulations reveal that the significance of the Keplerian signal in the F star is much more sensitive to wavelength. Unlike the K star, the removal of active lines from the F star greatly reduces the RV precision. In this case, our removal of a K star active line from an F star does not a provide a simple useful diagnostic because it has far less RV information and heavily relies on the strong active lines.

Digital Medical Interview Assistant AnCha for Obtaining the Medical History in General Medicine: Case study (Preprint)

2021 ◽  
Author(s):  
Selina Florence Regli ◽  
Floriana Gashi ◽  
Kerstin Denecke
Keyword(s):  
Medical History ◽  
User Interfaces ◽  
Pilot Trial ◽  
Age Groups ◽  
General Medicine ◽  
Time Frame ◽  
Practical Implementation ◽  
Medical Interview ◽  
Digital Tool ◽  
Dialog System

BACKGROUND Collecting information on the medical history of a patient is an important step during the diagnosing process. Besides the interrogation by the physician, computerized questionnaires are used to collect the data. To facilitate interaction, implementation of digital medical interview assistants (DMIA) using conversational user interfaces (CUI) gain in interest. OBJECTIVE The aim of this research is to assess patient’s and physician’s perceptions towards a DMIA with CUI. Beyond, we want to understand how such DMIA can be used in real-world context, what issues and barriers exist in their usage. METHODS We developed a web-based DMIA with CUI (referred to as AnCha for anamnesis chatbot) as a research prototype in a participative and iterative development process. We conducted a pilot trial in a practice for general medicine. Patient perceptions were collected and physicians were interrogated regarding usefulness of collected information. RESULTS 31 patients were approached, and 9 participants were included in the pilot trial; 3 conversation protocols were used by the physicians to prepare for the encounter. Participants spanned all age groups from digital natives (n=5), and digital workers (n=3) to digital seniors (n=1). Patients can easily interact with AnCha and are willing to provide information to the digital tool. They recognize benefits while using the dialog system compared to the existing process. Important insights into practical implementation and integration into practice workflows could be gained. CONCLUSIONS Providing information on complaints and medical history before the actual encounter is considered useful. In order to be supportive for physicians, information has to be made available in a sufficient time frame before the encounter. Future work has to assess in particular whether AnCha is also well accessible for digital seniors.

scholarly journals Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)

2014 ◽  
Vol 86 (12) ◽  
pp. 1931-1943 ◽  
Author(s):  
Jonathan Tennyson ◽  
Peter F. Bernath ◽  
Alain Campargue ◽  
Attila G. Császár ◽  
Ludovic Daumont ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
Pressure Effects ◽  
Task Group ◽  
High Resolution Spectroscopy ◽  
Line Shapes ◽  
Neutral Gas ◽  
Voigt Profile ◽  
Simplifying Assumptions ◽  
On Line

Abstract The report of an IUPAC Task Group, formed in 2011 on “Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory” (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety of alternative line-profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially Correlated quadratic-Speed-Dependent Hard-Collision profile (pCqSD-HCP) should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann–Tran profile (HTP). The HTP is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions.

scholarly journals A Novel Approach for Developing High-Resolution Sub-Fossil Peat Chronologies with 14C Dating

Radiocarbon ◽  
2004 ◽  
Vol 46 (1) ◽  
pp. 455-463 ◽  
Author(s):  
T H Donders ◽  
F Wagner ◽  
K van der Borg ◽  
A F M de Jong ◽  
H Visscher
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
20Th Century ◽  
Accelerator Mass Spectrometry ◽  
Meteorological Data ◽  
Time Frame ◽  
14C Dating ◽  
Novel Approach

Sub-fossil sections from a Florida wetland were accelerator mass spectrometry (AMS) dated and the sedimentological conditions were determined. 14C data were calibrated using a combined wiggle-match and 14C bomb-pulse approach. Repeatable results were obtained providing accurate peat chronologies for the last 130 calendar yr. Assessment of the different errors involved led to age models with 3–5 yr precision. This allows direct calibration of paleoenvironmental proxies with meteorological data. The time frame in which 14C dating is commonly applied can possibly be extended to include the 20th century.

scholarly journals The rotation curve, mass, light, and velocity distribution of M31

1970 ◽  
Vol 38 ◽  
pp. 51-60
Author(s):  
J. Einasto ◽  
U. Rümmel
Keyword(s):  
Spectroscopic Data ◽  
Total Mass ◽  
Rotation Curve ◽  
Mass Density ◽  
Major Axis ◽  
Deviation Angle ◽  
Andromeda Galaxy ◽  
The Galaxy ◽  
M 31 ◽  
Central Concentration

A model for the Andromeda galaxy, M 31, has been derived from the available radio, photometric, and spectroscopic data. The model consists of four components – the nucleus, the bulge, the disc, and the flat component.For all components the following functions have been found: the mass density; the mass-to-light ratio; the velocity dispersions in three perpendicular directions (for the plane of symmetry and the axis of the galaxy); the deviation angle of the major axis of the velocity ellipsoid from the plane of symmetry; the centroid velocity (for the plane of symmetry).Our model differs in two points from the models obtained by other authors: the central concentration of mass is higher (in the nucleus the mass-to-light ratio is about 170), and the total mass of the galaxy (200 × 109 solar masses) is smaller. The differences can be explained by different rotation curves adopted, and by attributing more weight to photometric and spectroscopic data in the case of our model.

scholarly journals The Massive Dark Corona Of Our Galaxy

1996 ◽  
Vol 173 ◽  
pp. 175-176
Author(s):  
K.C. Freeman
Keyword(s):  
Rotation Curve ◽  
Spiral Galaxies ◽  
Galactic Center ◽  
Galactic Disk ◽  
Galactic Rotation ◽  
Rotation Curves ◽  
Stellar Component ◽  
The Galaxy ◽  
Galactic Rotation Curve

From their rotation curves, most spiral galaxies appear to have massive dark coronas. The inferred masses of these dark coronas are typically 5 to 10 times the mass of the underlying stellar component. I will review the evidence that our Galaxy also has a dark corona. Our position in the galactic disk makes it difficult to measure the galactic rotation curve beyond about 20 kpc from the galactic center. However it does allow several other indicators of the total galactic mass out to very large distances. It seems clear that the Galaxy does indeed have a massive dark corona. The data indicate that the enclosed mass within radius R increases like M(R) ≈ R(kpc) × 1010M⊙, out to a radius of more than 100 kpc. The total galactic mass is at least 12 × 1011M⊙.

scholarly journals Phaseless Terahertz Coded-Aperture Imaging Based on Incoherent Detection

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 226 ◽  
Author(s):  
Long Peng ◽  
Chenggao Luo ◽  
Bin Deng ◽  
Hongqiang Wang ◽  
Yuliang Qin ◽  
...  
Keyword(s):  
High Resolution ◽  
High Speed ◽  
Phase Retrieval ◽  
Time Frame ◽  
Frame Rate ◽  
Future Research ◽  
Coded Aperture ◽  
Main Work ◽  
Coded Aperture Imaging ◽  
The Matrix

In this paper, we propose a phaseless terahertz coded-aperture imaging (PTCAI) method by using a single incoherent detector or an incoherent detection array. We at first analyze and model the system architecture, derive the matrix imaging equation, and then study the phase retrieval techniques to reconstruct the original target with high resolution. Numerical experiments are performed and the results show that the proposed method can significantly reduce the system complexity in the receiving process while maintaining high resolution imaging capability. Furthermore, the approach of using incoherent detection array instead of single detector is capable of decreasing the encoding and sampling times, and therefore helps to improve the imaging frame rate. In our future research, the method proposed in this paper will be experimentally tested and validated, and high-speed PTCAI at nearly real-time frame rates will be the main work.

scholarly journals Preterm birth disrupts the development of feeding and breathing coordination

2019 ◽  
Vol 126 (6) ◽  
pp. 1681-1686 ◽  
Author(s):  
Christopher J. Mayerl ◽  
Francois D. H. Gould ◽  
Laura E. Bond ◽  
Bethany M. Stricklen ◽  
Randal K. Buddington ◽  
...  
Keyword(s):  
Preterm Birth ◽  
High Resolution ◽  
Preterm Infants ◽  
High Speed ◽  
Clinical Care ◽  
Time Frame ◽  
Human Infants ◽  
High Resolution Data ◽  
Postnatal Maturation ◽  
Gestation Time

All mammals must breathe and breathe continuously from birth. Similarly, all mammals, including infants, have high functional demands for feeding. However, the pathway that food takes through the pharynx interrupts respiration. The coordination between swallowing and breathing is therefore critical for all infant mammals. Clinically, this coordination differs between term and preterm infants. However, the neurological mechanisms underlying this coordination and how it matures as infants grow are poorly understood. Here, we integrate high-resolution data from multiple physiologic processes across a longitudinal time frame to study suck-swallow-breathe dynamics in a preterm animal model, the infant pig. In doing so, we test the hypothesis that preterm birth will have an impact on some, but not all, behaviors associated with suck-swallow-breath performance. We hypothesize that coordination will be disrupted, reflecting incomplete connections in the brainstem. We found that preterm pigs became rhythmic and mature in sucking and swallowing behaviors, suggesting substantial postnatal maturation in the coordination of these behaviors. However, their ability to coordinate swallowing and breathing never developed. These results have implications for the nature of clinical care of human infants, as well as for how feeding processes develop in mammals. Clinically, they provide a foundation for developing interventions for preterm infants. Additionally, these results suggest that the lack of coordination between swallowing and breathing may be a significant factor in determining the minimum gestation time across mammals. NEW & NOTEWORTHY Preterm infants face a variety of challenges associated with safe feeding, but obtaining high-resolution longitudinal data to understand these challenges in humans is challenging. We used a pig model to acquire high-speed videofluoroscopic and respiratory inductance plethysmograph data throughout the nursing period to show that preterm birth does not have substantial impacts on the ability of infants to perform isolated behaviors. However, it does decrease the ability of preterm infants to coordinate among behaviors during feeding.

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