Primary production in over half of the world’s oceans is limited by fixed nitrogen availability. The main loss term from the fixed nitrogen inventory is the production of dinitrogen gas (N2) by ...heterotrophic denitrification or the more recently discovered autotrophic process, anaerobic ammonia oxidation (anammox). Oceanic oxygen minimum zones (OMZ) are responsible for about 35% of oceanic N2 production and up to half of that occurs in the Arabian Sea. Although denitrification was long thought to be the only loss term, it has recently been argued that anammox alone is responsible for fixed nitrogen loss in the OMZs. Here we measure denitrification and anammox rates and quantify the abundance of denitrifying and anammox bacteria in the OMZ regions of the Eastern Tropical South Pacific and the Arabian Sea. We find that denitrification rather than anammox dominates the N2 loss term in the Arabian Sea, the largest and most intense OMZ in the world ocean. In seven of eight experiments in the Arabian Sea denitrification is responsible for 87–99% of the total N2 production. The dominance of denitrification is reproducible using two independent isotope incubation methods. In contrast, anammox is dominant in the Eastern Tropical South Pacific OMZ, as detected using one of the isotope incubation methods, as previously reported. The abundance of denitrifying bacteria always exceeded that of anammox bacteria by up to 7- and 19-fold in the Eastern Tropical South Pacific and Arabian Sea, respectively. Geographic and temporal variability in carbon supply may be responsible for the different contributions of denitrification and anammox in these two OMZs. The large contribution of denitrification to N2 loss in the Arabian Sea indicates the global significance of denitrification to the oceanic nitrogen budget.
We present an integral field spectroscopic study of two nearby luminous infrared galaxies (LIRGs), IC 1623 and NGC 3256, which exhibit evidence of widespread shock excitation induced by ongoing ...merger activity. We show the importance of carefully separating excitation due to shocks versus excitation by H II regions and the usefulness of integral field unit data in interpreting the complex processes in LIRGs. Our analysis focuses primarily on the emission line gas, which is extensive in both systems and is a result of the abundant ongoing star formation as well as widespread LINER-like excitation from shocks. We use emission line ratio maps, line kinematics, line-ratio diagnostics, and new models as methods for distinguishing and analyzing shocked gas in these systems. We discuss how our results inform the merger sequence associated with local U/LIRGs and the impact that widespread shock excitation has on the interpretation of emission line spectra and derived quantities of both local and high-redshift galaxies.
ABSTRACT We present an integral field spectroscopic study of radiative shocks in 27 nearby ultraluminous and luminous infrared galaxies (U/LIRGs) from the Great Observatory All-sky LIRG Survey, a ...subset of the Revised Bright Galaxy Sample. Our analysis of the resolved spectroscopic data from the Wide Field Spectrograph focuses on determining the detailed properties of the emission-line gas, including a careful treatment of multicomponent emission-line profiles. The resulting information obtained from the spectral fits is used to map the kinematics of the gas, sources of ionizing radiation, and feedback present in each system. The resulting properties are tracked as a function of merger stage. Using emission-line flux ratios and velocity dispersions, we find evidence for widespread, extended shock excitation in many local U/LIRGs. These low-velocity shocks become an increasingly important component of the optical emission lines as a merger progresses. We find that shocks may account for as much as half of the H luminosity in the latest-stage mergers in our sample. We discuss some possible implications of our result and consider the presence of active galactic nuclei and their effects on the spectra in our sample.
Objective
To assess the association between the outcome of a woman's first pregnancy and risk of clinical cardiovascular disease risk factors.
Design
Prospective cohort study.
Setting and population
...Nurses’ Health Study II.
Methods
Multivariable‐adjusted Cox proportional hazards models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between first pregnancy outcome and hypertension, type 2 diabetes, and hypercholesterolemia.
Main outcome measures
Hypertension, type 2 diabetes, and hypercholesterolemia.
Results
Compared to women who reported a singleton live first birth, women with early spontaneous abortion (<12 weeks) had a greater rate of type 2 diabetes (HR: 1.20; 95% CI: 1.07–1.34) and hypercholesterolemia (HR: 1.06; 95% CI: 1.02–1.10), and a marginally increased rate of hypertension (HR: 1.05, 95% CI: 1.00–1.11). Late spontaneous abortion (12–19 weeks) was associated with an increased rate of type 2 diabetes (HR: 1.38; 95% CI: 1.14–1.65), hypercholesterolemia (HR: 1.11; 95% CI: 1.03–1.19), and hypertension (HR: 1.15; 95% CI: 1.05–1.25). The rates of type 2 diabetes (HR: 1.45; 95% CI: 1.13–1.87) and hypertension (HR: 1.15; 95% CI: 1.01–1.30) were higher in women who delivered stillbirth. In contrast, women whose first pregnancy ended in an induced abortion had lower rates of hypertension (HR: 0.87; 95% CI: 0.84–0.91) and type 2 diabetes (HR: 0.89; 95% CI: 0.79–0.99) than women with a singleton live birth.
Conclusions
Several types of pregnancy loss were associated with an increased rate of hypertension, type 2 diabetes, and hypercholesterolemia, which may provide novel insight into the pathways through which pregnancy outcomes and CVD are linked.
Tweetable
Pregnancy loss is associated with later maternal risk of hypertension, type 2 diabetes, and hypercholesterolemia.
Tweetable
Pregnancy loss is associated with later maternal risk of hypertension, type 2 diabetes, and hypercholesterolemia.
Oxygen is an essential regulator of cellular metabolism, survival, and proliferation. Cellular responses to oxygen levels are monitored, in part, by the transcriptional activity of the hypoxia ...inducible factors (HIFs). Under hypoxia, HIFs regulate a variety of pro-angiogenic and pro-glycolysis pathways. In solid cancers, regions of hypoxia are commonly present throughout the tissue because of the chaotic vascular architecture and regions of necrosis. In these regions, the hypoxic state fluctuates in a spatial and temporal manner. Transient hypoxic cycling causes an increase in the activity of the HIF proteins above what is typical for non-pathologic tissue. The extent of hypoxia strongly correlates to poor patient survival, therapeutic resistance and an aggressive tumour phenotype, but the full contribution of hypoxia and the HIFs to tumour biology is an area of active investigation. Recent reports link resistance to conventional therapies and the metastatic potential to a stem-like tumour population, termed cancer stem cells (CSCs). We and others have shown that within brain tumours CSCs reside in two niches, a perivascular location and the surrounding necrotic tissue. Restricted oxygen conditions increase the CSC fraction and promote acquisition of a stem-like state. Cancer stem cells are critically dependant on the HIFs for survival, self-renewal, and tumour growth. These observations and those from normal stem cell biology provide a new mechanistic explanation for the contribution of hypoxia to malignancy. Further, the presence of hypoxia in tumours may present challenges for therapy because of the promotion of CSC phenotypes even upon successful killing of CSCs. The current experimental evidence suggests that CSCs are plastic cell states governed by microenvironmental conditions, such as hypoxia, that may be critical for the development of new therapies targeted to disrupt the microenvironment.
GOALS: The Great Observatories All-Sky LIRG Survey Armus, L.; Mazzarella, J. M.; Evans, A. S. ...
Publications of the Astronomical Society of the Pacific,
06/2009, Volume:
121, Issue:
880
Journal Article
Peer reviewed
Open access
The Great Observatories All-Sky LIRG Survey (GOALS20) combines data from NASA’sSpitzer Space Telescope,
Chandra X-Ray Observatory,
Hubble Space Telescope(HST), andGalaxy Evolution Explorer(GALEX) ...observatories, together with ground-based data, into a comprehensive imaging and spectroscopic survey of over 200 low-redshift (
z < 0.088
z
<
0.088
), Luminous Infrared Galaxies (LIRGs). The LIRGs are a complete subset of theIRASRevised Bright Galaxy Sample (RBGS), which comprises 629 extragalactic objects with 60 μm flux densities above 5.24 Jy, and Galactic latitudes above five degrees. The LIRGs targeted in GOALS span the full range of nuclear spectral types defined via traditional optical line-ratio diagrams (type-1 and type-2 AGN, LINERs, and starbursts) as well as interaction stages (major mergers, minor mergers, and isolated galaxies). They provide an unbiased picture of the processes responsible for enhanced infrared emission in galaxies in the local Universe. As an example of the analytic power of the multiwavelength GOALS data set, we presentSpitzer, Chandra, HST,andGALEXimages and spectra for the interacting system VV 340 (IRAS
F14547 + 2449
F
14547
+
2449
). TheSpitzerMIPS imaging data indicates that between 80–95% of the total far-infrared emission (or about5 × 1011 L
⊙
5
×
10
11
L
⊙
) originates in VV 340 north. While theSpitzerIRAC colors of VV 340 north and south are consistent with star-forming galaxies, both theSpitzerIRS andChandraACIS data indicate the presence of an AGN in VV 340 north. The observed line fluxes, without correction for extinction, imply that the AGN accounts for less than 10%–20% of the observed infrared emission. The X-ray data are consistent with a heavily absorbed (
N
H
≥1024 cm-2
N
H
≥
10
24
cm
-
2
) AGN. The GALEX far and near-UV fluxes imply a extremely large infrared “excess” (IRX) for the system (FIR/Ffuv ∼ 81
F
IR
/
F
fuv
∼
81
) which is well above the correlation seen in starburst galaxies. Most of this excess is driven by VV 340 N, which has an IR excess of nearly 400. The VV 340 system seems to be comprised of two very different galaxies: an infrared luminous edge-on galaxy (VV 340 north) that dominates the long-wavelength emission from the system, which hosts a buried AGN; and a face-on starburst (VV 340 south) that dominates the short-wavelength emission.
A recent worldwide uptake of electric vehicles (EVs) has led to an increasing interest for the EV charging situation. A proper understanding of the former is required to understand charging needs and ...to dimension the corresponding infrastructure. In the paper, we develop models that allow us to approximate the steady-state distribution of State-of-Charge (SoC) levels for EVs at the beginning of the day and infer its dependence regarding the daily relative range, r defined as the ratio of mean daily-driven distance to the maximum range. The framework combines: (i) a generic parametric model for decision to charge in terms of the SoC and r; and (ii) a simulation model in which we utilize longitudinal log-data for a fleet of cars to track charging events and SoC over time. The model brings about several interesting use cases, of which two stand out. Firstly, it provides a simple parametric way of circumventing transient behaviour in SoC distributions when applied to simulation frameworks. Secondly, it offers a clear method to infer crucial information regarding EV fleets and the total energy storage potential. Such information is useful for vehicle-to-grid (V2G) applications in that it provides expected lower and upper bounds for the energy that can be stored and charged. The model is applied in a Danish context, and it is suggested that while a full electrification of the vehicle fleet could lead to significant stress on the power grid, it will at the same time hold a large potential for deploying V2G as an important mechanism to dampen the effect of temporal high-demand. The potential for V2G stems from a low battery utilization between charging events of approximately 40%, which in turn provides a large storage buffer that could be harnessed with little to no impact on EV utilization. Results also indicate that tapping into just half of the available buffer could serve the EV demand and also meet close to 50% of the household consumption.
•Estimation of steady-state distribution for decision to charge and level of SoC for EVs.•Models have simple parametric form and can be readily applied to different scenarios.•Assessment of general battery utilization and the interval between charging events.•Probabilistic assessment of power demand for different scenarios.•Estimation of storage capacity available for vehicle-to-grid systems.
We prepare mixtures of ultracold CaF molecules and Rb atoms in a magnetic trap and study their inelastic collisions. When the atoms are prepared in the spin-stretched state and the molecules in the ...spin-stretched component of the first rotationally excited state, they collide inelastically with a rate coefficient k_{2}=(6.6±1.5)×10^{-11} cm^{3}/s at temperatures near 100 μK. We attribute this to rotation-changing collisions. When the molecules are in the ground rotational state we see no inelastic loss and set an upper bound on the spin-relaxation rate coefficient of k_{2}<5.8×10^{-12} cm^{3}/s with 95% confidence. We compare these measurements to the results of a single-channel loss model based on quantum defect theory. The comparison suggests a short-range loss parameter close to unity for rotationally excited molecules, but below 0.04 for molecules in the rotational ground state.
Abstract
We present the results of a Hubble Space Telescope WFC3 near-UV and Advanced Camera for Surveys Wide Field Channel optical study into the star cluster populations of a sample of 10 luminous ...infrared galaxies (LIRGs) in the Great Observatories All-Sky LIRG Survey. Through integrated broadband photometry we have derived ages, masses, and extinctions for a total of 1027 star clusters in galaxies with
d
L
< 110 Mpc in order to avoid issues related to cluster bending. The measured cluster age distribution slope of
dN
/
d
τ
∝
τ
−
0.5
+
/
−
0.12
is steeper than what has been observed in lower-luminosity star-forming galaxies. Further, differences in the slope of the observed cluster age distribution between inner- (
dN
/
d
τ
∝
τ
−
1.07
+
/
−
0.12
) and outer-disk (
dN
/
d
τ
∝
τ
−
0.37
+
/
−
0.09
) star clusters provide evidence of mass-dependent cluster destruction in the central regions of LIRGs driven primarily by the combined effect of strong tidal shocks and encounters with massive giant molecular clouds. Excluding the nuclear ring surrounding the Seyfert 1 nucleus in NGC 7469, the derived cluster mass function (CMF;
dN
/
dM
∝
M
α
) offers marginal evidence for a truncation in the power law at
M
t
∼ 2×10
6
M
⊙
for our three most
cluster-rich
sources, which are all classified as early stage mergers. Finally, we find evidence of a flattening of the CMF slope of
dN
/
dM
∝
M
−
1.42
±
0.1
for clusters in late-stage mergers relative to early stage (
α
= −1.65 ± 0.02), which we attribute to an increase in the formation of massive clusters over the course of the interaction.
We report a detection of the baryon acoustic oscillation (BAO) feature in the three-dimensional correlation function of the transmitted flux fraction in the Lyα forest of high-redshift quasars. The ...study uses 48 640 quasars in the redshift range 2.1 ≤ z ≤ 3.5 from the Baryon Oscillation Spectroscopic Survey (BOSS) of the third generation of the Sloan Digital Sky Survey (SDSS-III). At a mean redshift z = 2.3, we measure the monopole and quadrupole components of the correlation function for separations in the range 20 h-1 Mpc < r < 200 h-1 Mpc. A peak in the correlation function is seen at a separation equal to (1.01 ± 0.03) times the distance expected for the BAO peak within a concordance ΛCDM cosmology. This first detection of the BAO peak at high redshift, when the universe was strongly matter dominated, results in constraints on the angular diameter distance DA and the expansion rate H at z = 2.3 that, combined with priors on H0 and the baryon density, require the existence of dark energy. Combined with constraints derived from cosmic microwave background observations, this result implies H(z = 2.3) = (224 ± 8) km s-1 Mpc-1, indicating that the time derivative of the cosmological scale parameter ȧ = H(z = 2.3)/(1 + z) is significantly greater than that measured with BAO at z ~ 0.5. This demonstrates that the expansion was decelerating in the range 0.7 < z < 2.3, as expected from the matter domination during this epoch. Combined with measurements of H0, one sees the pattern of deceleration followed by acceleration characteristic of a dark-energy dominated universe.
PDF
