The Ultraviolet Attenuation Law in Backlit Spiral Galaxies

(Abridged) The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use GALEX, XMM Optical Monitor, and HST data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with candidates provided by Galaxy Zoo participants. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law close to the Calzetti et al. (1994) form; the UV slope for the overall sample is substantially shallower than found by Wild et al. (2011), a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. This "grey" law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. The extrapolation needed to compare attenution between backlit galaxies at moderate redshifts, and local systems from SDSS data, is mild enough to allow use of galaxy overlaps to trace the cosmic history of dust. For NGC 2207, the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the ultraviolet, which opens the possibility that widespread diffuse dust dominates over dust in star-forming regions deep into the ultraviolet. Comparison with published radiative-transfer models indicates that the role of dust clumping dominates over differences in grain populations, at this spatial resolution.Comment: In press, Astronomical Journa

The use of fluorescence resonance energy transfer to monitor dynamic changes of lipid–DNA interactions during lipoplex formation

AbstractFluorescence resonance energy transfer (FRET) was used to monitor interactions between Cy3-labeled plasmid DNA and NBD-labeled cationic liposomes. FRET data show that binding of cationic liposomes to DNA occurs immediately upon mixing (within 1 min), but FRET efficiencies do not stabilize for 1–5 h. The time allowed for complex formation has effects on in vitro luciferase transfection efficiencies of DOPE-based lipoplexes; i.e., lipoplexes prepared with a 1-h incubation have much higher transfection efficiencies than samples with 1-min or 5-h incubations. The molar charge ratio of DOTAP to negatively charged phosphates in the DNA (DOTAP+/DNA−) also affected the interaction between liposomes and plasmid DNA, and interactions stabilized more rapidly at higher charge ratios. Lipoplexes formulated with DOPE were more resistant to high ionic strength than complexes formulated with cholesterol. Taken together, our data demonstrate that lipid–DNA interactions and in vitro transfection efficiencies are strongly affected by the time allowed for complex formation. This effect is especially evident in DOPE-based lipoplexes, and suggests that the time allowed for lipoplex formation is a parameter that should be carefully controlled in future studies

Criminal Justice Involvement and Young Adult Health: The Role of Adolescent Health Risks and Stress

Background: Although some studies have found that incarceration is associated with young adults\u27 poor health, confounding factors including adolescent health risks, and mediating influences such as stress have not been examined in the same study. We assessed whether variation in criminal justice system experience (none, arrest only, incarceration) influenced young adults\u27 self-reported depressive symptoms and poor physical health after accounting for prospective risks to health including adolescent health risks. We then assessed whether stress mediated associations between criminal justice involvement and the two health indicators. Methods: Data are from Toledo Adolescent Relationships Study (TARS) (n =990), which included young adults, age 22-29, who have matured during the era characterized by mass incarceration. The dependent variables included a depressive symptoms scale and self-reported poor health. The adolescent health risks included economic disadvantage, body mass index, delinquency, problems with drugs, and prior depressive symptoms. We considered stress as a mediating variable. Sociodemographic characteristics included race/ethnicity, age, and gender. We used ordinary least squares regression and logistic regression analyses. We tested gender, race/ethnicity, and age interactions. Results: In multivariable models, incarceration, and adolescent health risks (economic disadvantage, prior depression, problems with drugs) were associated with young adults\u27 depressive symptoms, and stress was a mediating influence. Adolescent delinquency and stress, but not incarceration, were significantly associated with young adults\u27 self-reported poor health. Conclusion: This study provided a more nuanced understanding of incarceration and health by accounting for several key confounding factors and testing stress as a mechanism underlying the association. Care for prisoner health during and after incarceration is important for successful reintegration

Interpreting the seasonal cycles of atmospheric oxygen and carbon dioxide concentrations at American Samoa Observatory

We present seven years of atmospheric O2/N2 ratio and CO2 concentration data measured from flask samples collected at American Samoa. These data are unusual, exhibiting higher short-term variability, and seasonal cycles not in phase with other sampling stations. The unique nature of atmospheric data from Samoa has been noted previously from measurements of CO2, methyl chloroform, and ozone. With our O2 data, we observe greater magnitude in the short-term variability, but, in contrast, no clear seasonal pattern to this variability. This we attribute to significant regional sources and sinks existing for O2 in both hemispheres, and a dependence on both the latitudinal and altitudinal origins of air masses. We also hypothesize that some samples exhibit a component of "older" air, demonstrating recirculation of air within the tropics. Our findings could be used to help constrain atmospheric transport models which are not well characterized in tropical regions

Criminal Justice Involvement and Young Adult Health: The Role of Adolescent Health Risks and Stress

Background: Although some studies have found that incarceration is associated with young adults’ poor health, confounding factors including adolescent health risks, and mediating influences such as stress have not been examined in the same study. We assessed whether variation in criminal justice system experience (none, arrest only, incarceration) influenced young adults’ self-reported depressive symptoms and poor physical health after accounting for prospective risks to health including adolescent health risks. We then assessed whether stress mediated associations between criminal justice involvement and the two health indicators. Methods: Data are from Toledo Adolescent Relationships Study (TARS) (n =990), which included young adults, age 22-29, who have matured during the era characterized by mass incarceration. The dependent variables included a depressive symptoms scale and self-reported poor health. The adolescent health risks included economic disadvantage, body mass index, delinquency, problems with drugs, and prior depressive symptoms. We considered stress as a mediating variable. Sociodemographic characteristics included race/ethnicity, age, and gender. We used ordinary least squares regression and logistic regression analyses. We tested gender, race/ethnicity, and age interactions. Results: In multivariable models, incarceration, and adolescent health risks (economic disadvantage, prior depression, problems with drugs) were associated with young adults’ depressive symptoms, and stress was a mediating influence. Adolescent delinquency and stress, but not incarceration, were significantly associated with young adults’ self-reported poor health. Conclusion: This study provided a more nuanced understanding of incarceration and health by accounting for several key confounding factors and testing stress as a mechanism underlying the association. Care for prisoner health during and after incarceration is important for successful reintegration

The Sudden Death of the Nearest Quasar

Galaxy formation is significantly modulated by energy output from supermassive black holes at the centers of galaxies which grow in highly efficient luminous quasar phases. The timescale on which black holes transition into and out of such phases is, however, unknown. We present the first measurement of the shutdown timescale for an individual quasar using X-ray observations of the nearby galaxy IC 2497, which hosted a luminous quasar no more than 70,000 years ago that is still seen as a light echo in `Hanny's Voorwerp', but whose present-day radiative output is lower by at least 2 and more likely by over 4 orders of magnitude. This extremely rapid shutdown provides new insights into the physics of accretion in supermassive black holes, and may signal a transition of the accretion disk to a radiatively inefficient state.Comment: 4 pages, 2 figures. Astrophysical Journal Letters, in pres

Interannual Variability in Methane and Nitrous Oxide Concentrations and Sea-Air Fluxes Across the North American Arctic Ocean (2015–2019)

Between 2015 and 2018, we collected approximately 2,000 water column measurements of methane (CH4) and nitrous oxide (N2O) concentrations in the North American Arctic Ocean during summer and early fall. We also obtained 25 measurements of CH4 and N2O concentrations in rivers along the Northwest Passage and Ellesmere Island in midsummer 2017–2019. Our results show that N2O is generated in the highly productive Bering and Chukchi Seas and transported northeastward, producing a persistent subsurface N2O peak in the Beaufort Sea. The Chukchi and Beaufort Sea sediments are a significant source of CH4 to the water column. These sedimentary sources and associated water column consumption display significant spatial gradients and interannual variability. CH4 isotope data demonstrate the importance of CH4 oxidation across the study region. We find that rivers are not a significant source of CH4 or N2O to the Arctic Ocean at the time of year sampled. The estimated annual sea-air flux across the study region (2.3 million km2) had a median (first quartile, third quartile) of 0.009 (0.002, 0.023) Tg CH4 y−1 and −0.003 (−0.013, 0.010) Tg N y−1. These results suggest that the North American Arctic Ocean currently plays a negligible role in global CH4 and N2O budgets. Our expansive data set, with observations at many repeat stations, provides a synopsis of present-day Arctic CH4 and N2O distributions and their range of variability, as well as a benchmark against which future climatedependent changes can be evaluated

Outcomes for children with acquired brain injury (ABI) admitted to acute neurorehabilitation

Aim:To evaluate an innovative paediatric neurorehabilitation model in relation to improving quality of neurorehabilitation and reducing length of stay (LOS) for children with acquired brain injury.Method:A process evaluation approach was conducted in line with Medical Research Council evaluation of complex interventions guidance. Analysis was conducted on routinely collected patient data from 2017 to 2018, including LOS and family feedback. Descriptive and inferential statistics were used for quantitative analysis and qualitative data was analysed thematically.Results:Outcomes for 70 children (0–16y, median age 5y, IQR 1–11y, 46 males, 24 females) referred to the service indicated improved function and reduced complexity of need. The mean LOS was 10.6 days compared to baseline mean LOS of 41 days (2011–2012). High satisfaction from the families was recorded; however, ongoing needs and service gaps regarding long‐term support were identified.Interpretation:This service model is effective in delivering quality paediatric neurorehabilitation, demonstrating a sustained impact on LOS, and positive patient outcome data and family feedback for this group of patients

The 1995 Georges Bank Stratification Study and moored array measurements

The 1995 Geoges Bank Stratification Study (GBSS) was the first intensive process study conducted as part of the U.S. GLOBEC Northwest Atlantic/Georges Bank field program. The GBSS was designed to investigate the physical processes which control the seasonal development of stratification along the southern flank of Georges Bank during spring and summer. Past work suggested that during this period, larval cod and haddock tended to aggregate to the thermocline on the southern flank where higher concentrations of their copepod prey were found. A moored array was deployed as part of GBSS to observe the onset and evolution of sesonal stratification over the southern flank with sufficient vertical and horizontal resolution that key physical processes could be identified and quantified. Moored current, temperature, and conductivity (salinity) measurements were made at three sites along the southern flank, one on the crest, and one on the northeast peak of the bank. Moored surface meteorological measurements were also made at one southern flank site to determine the surface wind stress and heat and moisture fluxes. The oceanographic and meteorological data collected with the GBSS array during January-August 1995 are presented in this report. Meteorological data collected on National Data Buoy Center environmental buoys 44011 (Georges Bank), 44008 (Nantucket Shoals), and 44005 (Gulf of Maine) are included in this report for completeness and comparison with the GBSS southern flank meteorological measurements.Funding was provided by the National Science Foundation under Grant Numbers OCE-98-06379 and OCE-98-06445

Novel quantification of regional fossil fuel CO2 reductions during COVID-19 lockdowns using atmospheric oxygen measurements

It is not currently possible to quantify regional-scale fossil fuel carbon dioxide (ffCO2) emissions with high accuracy in near real time. Existing atmospheric methods for separating ffCO2 from large natural carbon dioxide variations are constrained by sampling limitations, so that estimates of regional changes in ffCO2 emissions, such as those occurring in response to coronavirus disease 2019 (COVID-19) lockdowns, rely on indirect activity data. We present a method for quantifying regional signals of ffCO2 based on continuous atmospheric measurements of oxygen and carbon dioxide combined into the tracer "atmospheric potential oxygen"(APO). We detect and quantify ffCO2 reductions during 2020-2021 caused by the two U.K. COVID-19 lockdowns individually using APO data from Weybourne Atmospheric Observatory in the United Kingdom and a machine learning algorithm. Our APO-based assessment has near-real-time potential and provides high-frequency information that is in good agreement with the spread of ffCO2 emissions reductions from three independent lower-frequency U.K. estimates