1,220 research outputs found
Infrared Spectroscopy of the Diffuse Ionized Halo of NGC 891
We present infrared spectroscopy from the Spitzer Space Telescope at one disk
position and two positions at a height of 1 kpc from the disk in the edge-on
spiral NGC 891, with the primary goal of studying halo ionization. Our main
result is that the [Ne III]/[Ne II] ratio, which provides a measure of the
hardness of the ionizing spectrum free from the major problems plaguing optical
line ratios, is enhanced in the extraplanar pointings relative to the disk
pointing. Using a 2D Monte Carlo-based photo-ionization code which accounts for
the effects of radiation field hardening, we find that this trend cannot be
reproduced by any plausible photo-ionization model, and that a secondary source
of ionization must therefore operate in gaseous halos. We also present the
first spectroscopic detections of extraplanar PAH features in an external
normal galaxy. If they are in an exponential layer, very rough emission
scale-heights of 330-530 pc are implied for the various features. Extinction
may be non-negligible in the midplane and reduce these scale-heights
significantly. There is little significant variation in the relative emission
from the various features between disk and extraplanar environment. Only the
17.4 micron feature is significantly enhanced in the extraplanar gas compared
to the other features, possibly indicating a preference for larger PAHs in the
halo.Comment: 35 pages in ApJ preprint format, 8 figures, accepted for publication
in ApJ. Minor change to Introduction to give appropriate credit to earlier,
related wor
Subspecific Identification of Sharp-Tailed Grouse Samples from Montana
Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus) historically occupied much of the shrub-steppe habitat of the intermountain west, ranging from interior British Columbia south to California and Colorado. The subspecies has been extirpated from most of its range and currently exists in only scattered isolated populations. The last remnant populations in western Montana were located in the Tobacco Valley near Eureka and the Blackfoot Valley near Helmville. However, those populations were extirpated during the previous decade and the subspecies can no longer be confirmed in the state. A rangewide genetic analysis of sharp-tailed grouse in 2006 documented restricted gene flow based on an analysis of 45 tissue samples taken from Montana birds east of the continental divide. We extended that earlier analysis with a total of 133 tissue samples, including samples from western Montana birds extracted from museum skins collected in 1897, and compared these samples to other genetic profiles reported from across the species range. We compared these samples to test for genetic differences in an area where the reported distribution of the Columbian subspecies is geographically near populations from the plains subspecies (T. p. jamesi). We were able to assign subspecies classification to 126 of the 133 Montana samples, including all samples from west of the Continental Divide. All Montana samples conclusively typed out to the Plains subspecies. Our analysis identified 3 similar genetic clusters across sharptail populations: (1) Alberta, Colorado, Montana, North Dakota, South Dakota and Nebraska, (2) Washington, British Columbia and western Idaho, and (3) Utah and southern Idaho. Both microsatellite and control region sequence data indicate that sharp-tailed grouse from all localities in Montana are molecularly most similar to populations from the plains regions of Alberta to Nebraska, indicating that Montana birds share a relatively recent molecular history. It does not appear that the Continental Divide is a current or historical barrier to gene flow in sharp-tailed grouse
A self-consistent model of Galactic stellar and dust infrared emission and the abundance of polycyclic aromatic hydrocarbons
We present a self-consistent three-dimensional Monte-Carlo radiative transfer
model of the stellar and dust emission in the Milky-Way, and have computed
synthetic observations of the 3.6 to 100 microns emission in the Galactic
mid-plane. In order to compare the model to observations, we use the GLIMPSE,
MIPSGAL, and IRAS surveys to construct total emission spectra, as well as
longitude and latitude profiles for the emission. The distribution of stars and
dust is taken from the SKY model, and the dust emissivities includes an
approximation of the emission from polycyclic aromatic hydrocarbons in addition
to thermal emission. The model emission is in broad agreement with the
observations, but a few modifications are needed to obtain a good fit. Firstly,
by adjusting the model to include two major and two minor spiral arms rather
than four equal spiral arms, the fit to the longitude profiles for |l|>30
degrees can be improved. Secondly, introducing a deficit in the dust
distribution in the inner Galaxy results in a better fit to the shape of the
IRAS longitude profiles at 60 and 100 microns. With these modifications, the
model fits the observed profiles well, although it systematically
under-estimates the 5.8 and 8.0 microns fluxes. One way to resolve this
discrepancy is to increase the abundance of PAH molecules by 50% compared to
the original model, although we note that changes to the dust distribution or
radiation field may provide alternative solutions. Finally, we use the model to
quantify which stellar populations contribute the most to the heating of
different dust types, and which stellar populations and dust types contribute
the most to the emission at different wavelengths.Comment: Published in A&A. This version has been revised (compared to the
published version) to include additional references to previous work. Scripts
to reproduce the results in this paper can be found as supplementary material
on the A&A site, or at https://github.com/hyperion-rt/paper-galaxy-rt-mode
Clinical Factors Associated with the Non-Operative Airway Management of Patients with Robin Sequence.
BACKGROUND: The indications for surgical airway management in patients with Robin sequence (RS) and severe airway obstruction have not been well defined. While certain patients with RS clearly require surgical airway intervention and other patients just as clearly can be managed with conservative measures alone, a significant proportion of patients with RS present with a more confusing and ambiguous clinical course. The purpose of this study was to describe the clinical features and objective findings of patients with RS whose airways were successfully managed without surgical intervention.
METHODS: The authors retrospectively reviewed the medical charts of infants with RS evaluated for potential surgical airway management between 1994 and 2014. Patients who were successfully managed without surgical intervention were included. Patient demographics, nutritional and respiratory status, laboratory values, and polysomnography (PSG) findings were recorded.
RESULTS: Thirty-two infants met the inclusion criteria. The average hospital stay was 16.8 days (range, 5-70 days). Oxygen desaturation (
CONCLUSIONS: Nonsurgical airway management was successful in patients who demonstrated consistent weight gain and mild to moderate obstruction on PSG, with a mean AHI of/hour
Identification of a Deubiquitinating Enzyme as a Novel AGS3-Interacting Protein
Activator of G protein Signaling 3 (AGS3) is a receptor-independent G protein activator that has been implicated in multiple biological events such as brain development, neuroplasticity and addiction, cardiac function, Golgi structure/function, macroautophagy and metabolism. However, how AGS3 is regulated is little known. We demonstrate here that AGS3 interacts with a ubiquitin specific protease USP9x, and this interaction is at least partially mediated through the C-terminal G protein regulatory domain of AGS3. Knockdown of USP9x causes a moderate reduction in the level of AGS3. In contrast, overexpression of either USP9x or its deubiquitinating domain UCH increases the amount of AGS3, whereas expression of the mutant UCH domain that lacks deubiquitinating activity does not have the same effect. As previously observed in AGS3 knockdown cells, the localization of several marker proteins of the late Golgi compartments is disturbed in cells depleted of USP9x. Taken together, our study suggests that USP9x can modulate the level of a subpopulation of AGS3, and this modulation plays a role in regulating the structure of the late Golgi compartments. Finally, we have found that levels of AGS3 and USP9x are co-regulated in the prefrontal cortex of rats withdrawn from repeated cocaine treatment. In conjunction with the above data, this observation indicates a potential role of USP9X in the regulation of the AGS3 level during cocaine-induced neuroplasticity
Energetic Costs of Testosterone in Two Subsistence Populations
Objective
Testosterone plays a role in mediating energetic trade-offs between growth, maintenance, and reproduction. Investments in a high testosterone phenotype trade-off against other functions, particularly survival-enhancing immune function and cellular repair; thus only individuals in good condition can maintain both a high testosterone phenotype and somatic maintenance. While these effects are observed in experimental manipulations, they are difficult to demonstrate in free-living animals, particularly in humans. We hypothesize that individuals with higher testosterone will have higher energetic expenditures than those with lower testosterone. Methods
Total energetic expenditure (TEE) was quantified using doubly labeled water in n = 40 Tsimane forager-horticulturalists (50% male, 18–87 years) and n = 11 Hadza hunter-gatherers (100% male, 18–65 years), two populations living subsistence lifestyles, high levels of physical activity, and high infectious burden. Urinary testosterone, TEE, body composition, and physical activity were measured to assess potential physical and behavioral costs associated with a high testosterone phenotype. Results
Endogenous male testosterone was significantly associated with energetic expenditure, controlling for fat free mass; a one standard deviation increase in testosterone is associated with the expenditure of an additional 96–240 calories per day. Discussion
These results suggest that a high testosterone phenotype, while beneficial for male reproduction, is also energetically expensive and likely only possible to maintain in healthy males in robust condition
A Dysregulated Endocannabinoid-Eicosanoid Network Supports Pathogenesis in a Mouse Model of Alzheimer's Disease
SummaryAlthough inflammation in the brain is meant as a defense mechanism against neurotoxic stimuli, increasing evidence suggests that uncontrolled, chronic, and persistent inflammation contributes to neurodegeneration. Most neurodegenerative diseases have now been associated with chronic inflammation, including Alzheimer's disease (AD). Whether anti-inflammatory approaches can be used to treat AD, however, is a major unanswered question. We recently demonstrated that monoacylglycerol lipase (MAGL) hydrolyzes endocannabinoids to generate the primary arachidonic acid pool for neuroinflammatory prostaglandins. In this study, we show that genetic inactivation of MAGL attenuates neuroinflammation and lowers amyloid β levels and plaques in an AD mouse model. We also find that pharmacological blockade of MAGL recapitulates the cytokine-lowering effects through reduced prostaglandin production, rather than enhanced endocannabinoid signaling. Our findings thus reveal a role of MAGL in modulating neuroinflammation and amyloidosis in AD etiology and put forth MAGL inhibitors as a potential next-generation strategy for combating AD
Interstellar Extinction and Long-Period Variables in the Galactic Center
We use the Spitzer IRAC catalogue of the Galactic Center (GC) point sources
(Ramirez et al. 2008) and combine it with new isochrones (Marigo et al. 2008)
to derive extinctions based on photometry of red giants and asymptotic giant
branch (AGB) stars. This new extinction map extends to much higher values of Av
than previoulsy available. Our new extinction map of the GC region covers 2.0 x
1.4 degree (280 x 200 pc at a distance of 8 kpc). We apply it to deredden the
LPVs found by Glass et al. (2001) near the GC. We make period-magnitude
diagrams and compare them to those from other regions of different metallicity.
The Glass-LPVs follow well-defined period-luminosity relations (PL) in the
IRAC filter bands at 3.6, 4.5, 5.8, and 8.0 micron. The period-luminosity
relations are similar to those in the Large Magellanic Cloud, suggesting that
the PL relation in the IRAC bands is universal. We use ISOGAL data to derive
mass-loss rates and find for the Glass-LPV sample some correlation between
mass-loss and pulsation period, as expected theoretically.The GC has an excess
of high luminosity and long period LPVs compared to the Bulge, which supports
previous suggestions that it contains a younger stellar population.Comment: 12 pages, 11 figures accepted for publication in Astronomy &
Astrophysic
Initial phases of massive star formation in high infrared extinction clouds. I. Physical parameters
The earliest phases of massive star formation are found in cold and dense
infrared dark clouds (IRDCs). Since the detection method of IRDCs is very
sensitive to the local properties of the background emission, we present here
an alternative method to search for high column density in the Galactic plane
by using infrared extinction maps. We find clouds between 1 and 5 kpc, of which
many were missed by previous surveys. By studying the physical conditions of a
subsample of these clouds, we aim at a better understanding of the initial
conditions of massive star formation. We made extinction maps of the Galactic
plane based on the 3.6-4.5 microns color excess between the two shortest
wavelength Spitzer IRAC bands, reaching to visual extinctions of ~100 mag and
column densities of 9x10^22 cm^-2. From this we compiled a new sample of cold
and compact high extinction clouds. We used the MAMBO array at the IRAM 30m
telescope to study the morphology, masses and densities of the clouds and the
dense clumps within them. The latter were followed up by pointed ammonia
observations with the 100m Effelsberg telescope, to determine rotational
temperatures and kinematic distances. Extinction maps of the Galactic plane
trace large scale structures such as the spiral arms. The 1.2 mm emission maps
reveal that the high extinction clouds contain extended cold dust emission,
from filamentary structures to still diffuse clouds. Most of the clouds are
dark in 24 microns, but several show already signs of star formation via maser
emission or bright infrared sources, suggesting that the high extinction clouds
contain a variety of evolutionary stages. The observations suggest an
evolutionary scheme from dark, cold and diffuse clouds, to clouds with a
stronger 1.2 mm peak and to finally clouds with many strong 1.2 mm peaks, which
are also warmer, more turbulent and already have some star formation signposts.Comment: 26 pages, 14 figures, 9 tables. Accepted for publication in Astronomy
and Astrophysics, small corrections implemente
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