ABSTRACT
The problem of the extent of habitable zones in different kinds of galaxies is one of the outstanding challenges for contemporary astrobiology. In the present study, we investigate ...habitability in a large sample of simulated galaxies from the illustris Project in order to at least roughly quantify the hospitality to life of different galactic types. The pioneering study of Dayal et al. is critically examined and some of its results are amended. In particular, we find a tentative evidence for a second mode of galactic habitability comprising metal-rich dwarfs similar to IC 225, LMC, or M32. The role of the galactic environment and the observation-selection effects is briefly discussed and prospects for further research on the topic outlined.
ABSTRACT
We investigate the origins of the uniquely elongated (1067 kpc in length and 97 kpc in width) association of galaxies known as NGC 3109, positioned at ∼ 1 Mpc from the Local Group (LG). To ...understand its likely origins, we have conducted a series of numerical simulations where the NGC 3109 association is represented as a regular, gravitationally bound N-body system of five galaxies, stripped from most of their dark matter due to previous tidal effects. The association evolves for 10 Gyr in an analytical potential representing the influence of the LG. We find that a loosely gravitationally bound system of five galaxies in a hyperbolic orbit toward the LG evolves into a tidally elongated structure similar to recent observations of NGC 3109. In this proof of concept model, the N-body simulations can reproduce the observations of the NGC 3109 association, such as its dimensions, as well as the radial velocity and distance from the LG.
In this work, we model the observed evolution in comoving number density of Lyman α blobs (LABs) as a function of redshift. Our model calculates LAB emission both from cooling radiation from the ...intergalactic gas accreting on to galaxies and from star formation (SF). We have used a dark matter (DM) cosmological simulation to which we applied empirical recipes for Ly α emission produced by cooling radiation and SF in every halo. Unlike previous work, the simulated volume in the DM simulation is large enough to produce an average LAB number density. For a range of redshifts, z ∼ 1–7, we compare our results with the observed luminosity functions of LABs and Lyman α emitters. Our cooling radiation luminosities appear to be too small to explain LAB luminosities at all redshifts. In contrast, for SF we obtained a good agreement with observed luminosity functions at all redshifts studied. We also discuss uncertainties that could influence the results obtained.
In this paper we present halo statistics analysis of a ?CDM N body
cosmological simulation (from first halo formation until z = 0). We study
mean major merger rate as a function of time, where for ...time we consider
both per redshift and per Gyr dependence. For latter we find that it scales
as the well known power law (1 + z)n for which we obtain n = 2.4. The halo
mass function and halo growth function are derived and compared both with
analytical and empirical fits. We analyse halo growth through out entire
simulation, making it possible to continuously monitor evolution of halo
number density within given mass ranges. The halo formation redshift is
studied exploring possibility for a new simple preliminary analysis during
the simulation run. Visualization of the simulation is portrayed as well. At
redshifts z = 0?7 halos from simulation have good statistics for further
analysis especially in mass range of 1011 ? 1014 M./h.
Background
Comorbidities occur frequently in persons with multiple sclerosis (MS). The aim of the present study was to determine the prevalence of the most common comorbidities in the population of ...MS patients in Belgrade, Serbia.
Material and methods
Data on diagnosed and fully documented comorbidities were taken from the Belgrade MS population registry. The list of explored comorbidities included cardiovascular, malignant, and autoimmune diseases; psychiatric disorders; epilepsy; and type 2 diabetes. In the data analysis, crude, age- and gender-specific, and age-adjusted prevalence was calculated. Additionally, comorbidities were analyzed in patients with various MS phenotypes.
Results
The most prevalent group of comorbidities were psychiatric (prevalence (Prev) = 20.59%, 95% CI 19.10–22.17) and cardiovascular comorbidities (Prev = 15.23%, 95% CI 13.93–16.63). The most prevalent single comorbidities were depression (Prev = 11.82%, 95% CI 10.64–13.11) and hypertension (Prev = 11.41%, 95% CI 10.25–12.68). Type 2 diabetes was significantly more prevalent in patients with primary progressive MS compared with the patients with relapsing-remitting and secondary progressive MS (
p
< 0.001). We found statistically significant positive correlation between number of comorbidities and progression index (
p
< 0.001). Patients treated with disease-modifying therapies (DMTs) had significantly higher risk of developing comorbidity, after treatment initiation, compared with those who were untreated (
p
= 0.001).
Conclusions
Our study demonstrated high prevalence of comorbidities in persons with MS, with psychiatric and cardiovascular diseases being the most common. Furthermore, our findings confirmed the association of comorbidities with progression of disability and emphasized their role in treatment decision-making in MS.
In this work, we model the observed evolution in comoving number density of Lyman α blobs (LABs) as a function of redshift. Our model calculates LAB emission both from cooling radiation from the ...intergalactic gas accreting on to galaxies and from star formation (SF). We have used a dark matter (DM) cosmological simulation to which we applied empirical recipes for Ly α emission produced by cooling radiation and SF in every halo. Unlike previous work, the simulated volume in the DM simulation is large enough to produce an average LAB number density. For a range of redshifts, z ~ 1-7, we compare our results with the observed luminosity functions of LABs and Lyman α emitters. Our cooling radiation luminosities appear to be too small to explain LAB luminosities at all redshifts. In contrast, for SF we obtained a good agreement with observed luminosity functions at all redshifts studied. We also discuss uncertainties that could influence the results obtained.
Self-efficacy's role in determining perceived and sustained effort during an isometric handgrip task was assessed using a repeated measures experimental design. Moderately active, predominantly ...Caucasian, participants (male = 33, female = 39, M = 19.18 years, SD = .74) were recruited from the southeastern United States. Participants were randomly assigned to one of three groups: High-efficacy (HE), low-efficacy (LE), or control. Efficacy expectations were manipulated via false performance feedback. During the task participants provided differentiated ratings of perceived effort at 15-s intervals. Effort tolerance was determined by the length of time the participant could maintain the task. Repeated measures (RM) multivariate analysis of variance (MANOVA) indicated the HE group found the task less strenuous and more enjoyable than the LE or control group. Furthermore, the HE group demonstrated greater tolerance of the task than either the LE or control group. These findings imply that self-efficacy has a major role in enhancing performance and physical effort tolerance.
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