1,171 research outputs found
Molecular Gas and Star Formation in the Cartwheel
Atacama Large Millimeter/submillimeter Array (ALMA) 12CO(J=1-0) observations
are used to study the cold molecular ISM of the Cartwheel ring galaxy and its
relation to HI and massive star formation (SF). CO moment maps find
M of H associated with the inner ring
(72%) and nucleus (28%) for a Galactic I(CO)-to-N(H2) conversion factor
(). The spokes and disk are not detected. Analysis of the
inner ring's CO kinematics show it to be expanding ( km
s) implying an Myr age. Stack averaging reveals CO emission
in the starburst outer ring for the first time, but only where HI surface
density () is high, representing M for a metallicity appropriate
, giving small ( M
pc), molecular fraction (), and H depletion
timescales ( Myr). Elsewhere in the outer ring
M pc,
and Myr (all ). The inner ring and
nucleus are H-dominated and are consistent with local spiral SF laws.
in the outer ring appears independent of ,
or . The ISM's long confinement in the
robustly star forming rings of the Cartwheel and AM0644-741 may result in
either a large diffuse H component or an abundance of CO-faint low column
density molecular clouds. The H content of evolved starburst rings may
therefore be substantially larger. Due to its lower and age
the Cartwheel's inner ring has yet to reach this state. Alternately, the outer
ring may trigger efficient SF in an HI-dominated ISM.Comment: 10-pages text; 5-figure
If cooperation is likely punish mildly: Insights from economic experiments based on the snowdrift game
Punishment may deter antisocial behavior. Yet to punish is costly, and the
costs often do not offset the gains that are due to elevated levels of
cooperation. However, the effectiveness of punishment depends not only on how
costly it is, but also on the circumstances defining the social dilemma. Using
the snowdrift game as the basis, we have conducted a series of economic
experiments to determine whether severe punishment is more effective than mild
punishment. We have observed that severe punishment is not necessarily more
effective, even if the cost of punishment is identical in both cases. The
benefits of severe punishment become evident only under extremely adverse
conditions, when to cooperate is highly improbable in the absence of sanctions.
If cooperation is likely, mild punishment is not less effective and leads to
higher average payoffs, and is thus the much preferred alternative. Presented
results suggest that the positive effects of punishment stem not only from
imposed fines, but may also have a psychological background. Small fines can do
wonders in motivating us to chose cooperation over defection, but without the
paralyzing effect that may be brought about by large fines. The later should be
utilized only when absolutely necessary.Comment: 15 pages, 6 figures; accepted for publication in PLoS ON
Antiviral Activity of Influenza A Virus Defective Interfering Particles against SARS-CoV-2 Replication In Vitro through Stimulation of Innate Immunity
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) emerged in late 2019 and resulted in a devastating pandemic. Although the first approved vaccines were already administered by the end of 2020, worldwide vaccine availability is still limited. Moreover, immune escape variants of the virus are emerging against which the current vaccines may confer only limited protection. Further, existing antivirals and treatment options against COVID-19 show only limited efficacy. Influenza A virus (IAV) defective interfering particles (DIPs) were previously proposed not only for antiviral treatment of the influenza disease but also for pan-specific treatment of interferon (IFN)-sensitive respiratory virus infections. To investigate the applicability of IAV DIPs as an antiviral for the treatment of COVID-19, we conducted in vitro co-infection experiments with cell culture-derived DIPs and the IFN-sensitive SARS-CoV-2 in human lung cells. We show that treatment with IAV DIPs leads to complete abrogation of SARS-CoV-2 replication. Moreover, this inhibitory effect was dependent on janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling. Further, our results suggest boosting of IFN-induced antiviral activity by IAV DIPs as a major contributor in suppressing SARS-CoV-2 replication. Thus, we propose IAV DIPs as an effective antiviral agent for treatment of COVID-19, and potentially also for suppressing the replication of new variants of SARS-CoV-2
Dependence of radio halo properties on star formation activity and galaxy mass
We investigate the relation between the existence and size of radio halos,
which are believed to be created by star formation (SF) related energy input
into the interstellar medium, and other galaxy properties, most importantly
star formation activity and galaxy mass. Based on radio continuum and H-alpha
observations of a sample of seven late-type spiral galaxies we find a direct,
linear correlation of the radial extent of gaseous halos on the size of the
actively star-forming parts of the galaxy disks. Data of a larger sample of 22
galaxies indicate that the threshold energy input rate into the disk ISM per
unit surface area for the creation of a gaseous halo depends on the mass
surface density of the galaxy, in the sense that a higher threshold must be
surpassed for galaxies with a higher surface density. Because of the good
prediction of the existence of a radio halo from these two parameters, we
conclude that they are important, albeit not the only contributors. The
compactness of the SF-related energy input is also found to be a relevant
factor. Galaxies with relatively compact SF distributions are more likely to
have gaseous halos than others with more widespread SF activity. These results
quantify the so-called "break-out" condition for matter to escape from galaxy
disks, as used in all current models of the interstellar medium and first
defined by Norman and Ikeuchi (1989).Comment: accepted for publication in Astronomy & Astrophysic
Measures of insulin sensitivity, leptin, and adiponectin concentrations in cats in diabetic remission compared to healthy control cats
Objectives: Firstly, to compare differences in insulin, adiponectin, leptin, and measures of insulin sensitivity between diabetic cats in remission and healthy control cats, and determine whether these are predictors of diabetic relapse. Secondly, to determine if these hormones are associated with serum metabolites known to differ between groups. Thirdly, if any of the hormonal or identified metabolites are associated with measures of insulin sensitivity.
Animals: Twenty cats in diabetic remission for a median of 101 days, and 21 healthy matched control cats.
Methods: A casual blood glucose measured on admission to the clinic. Following a 24 h fast, a fasted blood glucose was measured, and blood sample taken for hormone (i.e., insulin, leptin, and adiponectin) and untargeted metabolomic (GC-MS and LC-MS) analysis. A simplified IVGGT (1 g glucose/kg) was performed 3 h later. Cats were monitored for diabetes relapse for at least 9 months (270 days).
Results: Cats in diabetic remission had significantly higher serum glucose and insulin concentrations, and decreased insulin sensitivity as indicated by an increase in HOMA and decrease in QUICKI and Bennett indices. Leptin was significantly increased, but there was no difference in adiponectin (or body condition score). Several significant correlations were found between insulin sensitivity indices, leptin, and serum metabolites identified as significantly different between remission and control cats. No metabolites were significantly correlated with adiponectin. No predictors of relapse were identified in this study.
Conclusion and clinical importance: Insulin resistance, an underlying factor in diabetic cats, persists in diabetic remission. Cats in remission should be managed to avoid further exacerbating insulin resistance
Metabolic profiling of diabetic cats in remission
Background: The majority of diabetic cats in remission have abnormal glucose tolerance, and approximately one third relapse within 1 year. Greater understanding of the metabolic characteristics of diabetic cats in remission, and predictors of relapse is required to effectively monitor and manage these cats.
Objectives: To identify and compare differences in plasma metabolites between diabetic cats in remission and healthy control cats using a metabolomics approach. Secondly, to assess whether identified metabolites are predictors of diabetic relapse.
Animals: Twenty cats in diabetic remission for a median of 101 days, and 22 healthy matched control cats.
Methods: Cats were admitted to a clinic, and casual blood glucose was recorded. After a 24 h fast, blood glucose concentration was measured, then a blood sample was taken for metabolomic (GCMS and LCMS) analyses. Three hours later, a simplified intravenous glucose tolerance test (1 g glucose/kg) was performed. Cats were monitored for diabetes relapse for at least 9 months (270 days) after baseline testing.
Results: Most cats in remission continued to display impaired glucose tolerance. Concentrations of 16 identified metabolites differed (P ≤ 0.05) between remission and control cats: 10 amino acids and stearic acid (all lower in remission cats), and glucose, glycine, xylitol, urea and carnitine (all higher in remission cats). Moderately close correlations were found between these 16 metabolites and variables assessing glycaemic responses (most |r| = 0.31 to 0.69). Five cats in remission relapsed during the study period. No metabolite was identified as a predictor of relapse.
Conclusion and clinical importance: This study shows that cats in diabetic remission have abnormal metabolism
Near-field interactions between metal nanoparticle surface plasmons and molecular excitons in thin-films: part I: absorption
In this and the following paper (parts I and II, respectively), we systematically study the interactions between surface plasmons of metal nanoparticles (NPs) with excitons in thin-films of organic media. In an effort to exclusively probe near-field interactions, we utilize spherical Ag NPs in a size-regime where far-field light scattering is negligibly small compared to absorption. In part I, we discuss the effect of the presence of these Ag NPs on the absorption of the embedding medium by means of experiment, numerical simulations, and analytical calculations, all shown to be in good agreement. We observe absorption enhancement in the embedding medium due to the Ag NPs with a strong dependence on the medium permittivity, the spectral position relative to the surface plasmon resonance frequency, and the thickness of the organic layer. By introducing a low index spacer layer between the NPs and the organic medium, this absorption enhancement is experimentally confirmed to be a near field effect In part II, we probe the impact of the Ag NPs on the emission of organic molecules by time-resolved and steady-state photoluminescence measurements
Beliefs about others' intentions determine whether cooperation is the faster choice
Is collaboration the fast choice for humans? Past studies proposed that cooperation is a behavioural default, based on Response Times (RT) findings. Here we contend that the individual’s reckoning of the immediate social environment shapes her predisposition to cooperate and, hence, response latencies. In a social dilemma game, we manipulate the beliefs about the partner’s intentions to cooperate and show that they act as a switch that determines cooperation and defection RTs; when the partner’s intention to cooperate is perceived as high, cooperation choices are speeded up, while defection is slowed down. Importantly, this social context effect holds across varying expected payoffs, indicating that it modulates behaviour regardless of choices’ similarity in monetary terms. Moreover, this pattern is moderated by individual variability in social preferences: Among conditional cooperators, high cooperation beliefs speed up cooperation responses and slow down defection. Among free-riders, defection is always faster and more likely than cooperation, while high cooperation beliefs slow down all decisions. These results shed new light on the conflict of choices account of response latencies, as well as on the intuitive cooperation hypothesis, and can help to correctly interpret and reconcile previous, apparently contradictory results, by considering the role of context in social dilemmas
The Energetics of Molecular Gas in NGC 891 from H2 and FIR Spectroscopy
We have studied the molecular hydrogen energetics of the edge-on spiral
galaxy NGC\,891, using a 34-position map in the lowest three pure rotational
H lines observed with the Spitzer Infrared Spectrograph. The S(0), S(1),
and S(2) lines are bright with an extinction corrected total luminosity of
L, or 0.09\% of the total-infrared luminosity
of NGC\,891. The H line ratios are nearly constant along the plane of the
galaxy -- we do not observe the previously reported strong drop-off in the
S(1)/S(0) line intensity ratio in the outer regions of the galaxy, so we find
no evidence for the very massive cold CO-free molecular clouds invoked to
explain the past observations. The H level excitation temperatures increase
monotonically indicating more than one component to the emitting gas. More than
99\% of the mass is in the lowest excitation (T 125 K) ``warm''
component. In the inner galaxy, the warm H emitting gas is 15\% of
the CO(1-0)-traced cool molecular gas, while in the outer regions the fraction
is twice as high. This large mass of warm gas is heated by a combination of the
far-UV photons from stars in photo-dissociation regions (PDRs) and the
dissipation of turbulent kinetic energy. Including the observed far-infrared
[OI] and [CII] fine-structure line emission and far-infrared continuum emission
in a self-consistent manner to constrain the PDR models, we find essentially
all of the S(0) and most (70\%) of the S(1) line arises from low excitation
PDRs, while most (80\%) of the S(2) and the remainder of the S(1) line emission
arises from low velocity microturbulent dissipation.Comment: Accepted for publication in The Astrophysical Journal. Figure 10
available at http://www.physics.uoc.gr/~vassilis/papers/ngc891.pd
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