77 research outputs found
Spitzer Mid-Infrared Spectroscopy of Infrared Luminous Galaxies at z~2 III: Far-IR to Radio Properties and Optical Spectral Diagnostics
We present the far-IR, millimeter, and radio photometry as well as optical
and near-IR spectroscopy of a sample of 48 z~1-3 Spitzer-selected ULIRGs with
IRS mid-IR spectra. Our goals are to compute their bolometric emission, and to
determine both the presence and relative strength of their AGN and starburst
components. We find that strong-PAH sources tend to have higher 160um and 1.2mm
fluxes than weak-PAH sources. The depth of the 9.7um silicate feature does not
affect MAMBO detectability. We fit the far-IR SEDs of our sample and find an
average ~7x10^{12}Lsun for our z>1.5 sources. Spectral decomposition
suggests that strong-PAH sources typically have ~20-30% AGN fractions. Weak-PAH
sources by contrast tend to have >~70% AGN fractions, with a few sources having
comparable contributions of AGN and starbursts. The optical line diagnostics
support the presence of AGN in the bulk of the weak-PAH sources. With one
exception, our sources are narrow-line sources, show no obvious correspondence
between the optical extinction and the silicate feature depth, and, in two
cases, show evidence for outflows. Radio AGN are present in both strong-PAH and
weak-PAH sources. This is supported by our sample's far-IR-to-radio ratios (q)
being consistently below the average value of 2.34 for local star-forming
galaxies. We use survival analysis to include the lower-limits given by the
radio-undetected sources, arriving at =2.07+/-0.01 for our z>1.5 sample. In
total, radio and, where available, optical line diagnostics support the
presence of AGN in 57% of the z>1.5 sources, independent of IR-based
diagnostics. For higher-z sources, the AGN luminosities alone are estimated to
be >10^{12}Lsun, which, supported by the [OIII] luminosities, implies that the
bulk of our sources host obscured quasars.Comment: 22 pages, 14 figures, accepted for publication in Ap
Molecular Gas in the Lensed Lyman Break Galaxy cB58
We have used the IRAM Plateau de Bure Interferometer to map CO(3-2) emission
from the gravitationally lensed Lyman break galaxy MS1512-cB58. This is the
first detection of a molecular emission line in any Lyman break system; its
integrated intensity implies a total molecular gas mass of 6.6e9 Msun, while
its width implies a dynamical mass of 1.0e10 csc^2i Msun (for a flat Lambda=0.7
cosmology). These estimates are in excellent concordance with nearly all
parameters of the system measured at other wavelengths, and yield a consistent
picture of past and future star formation with no obvious discrepancies
requiring explanation by differential lensing. In particular, we find that the
age and remaining lifetime of the current episode of star formation are likely
to be similar; the surface densities of star formation and molecular gas mass
are related by a Schmidt law; and the fraction of baryonic mass already
converted into stars is sufficient to account for the observed enrichment of
the interstellar medium to 0.4 Zsun. Barring substantial gas inflow or a major
merger, the stars forming in the current episode will have mass and coevality
at z=0 similar to those of a spiral bulge. Assuming cB58 is a typical Lyman
break galaxy apart from its magnification, its global parameters suggest that
the prescriptions for star formation used in some semi-analytic models of
galaxy evolution require moderate revision, although the general prediction
that gas mass fraction should increase with redshift is validated. [abridged]Comment: 41 pages, 6 figures, accepted by Ap
COLD GASS, an IRAM Legacy Survey of Molecular Gas in Massive Galaxies: II. The non-universality of the Molecular Gas Depletion Timescale
We study the relation between molecular gas and star formation in a
volume-limited sample of 222 galaxies from the COLD GASS survey, with
measurements of the CO(1-0) line from the IRAM 30m telescope. The galaxies are
at redshifts 0.025<z<0.05 and have stellar masses in the range
10.0<log(M*/Msun)<11.5. The IRAM measurements are complemented by deep Arecibo
HI observations and homogeneous SDSS and GALEX photometry. A reference sample
that includes both UV and far-IR data is used to calibrate our estimates of
star formation rates from the seven optical/UV bands. The mean molecular gas
depletion timescale, tdep(H2), for all the galaxies in our sample is 1 Gyr,
however tdep(H2) increases by a factor of 6 from a value of ~0.5 Gyr for
galaxies with stellar masses of 10^10 Msun to ~3 Gyr for galaxies with masses
of a few times 10^11 Msun. In contrast, the atomic gas depletion timescale
remains contant at a value of around 3 Gyr. This implies that in high mass
galaxies, molecular and atomic gas depletion timescales are comparable, but in
low mass galaxies, molecular gas is being consumed much more quickly than
atomic gas. The strongest dependences of tdep(H2) are on the stellar mass of
the galaxy (parameterized as log tdep(H2)= (0.36+/-0.07)(log M* -
10.70)+(9.03+/-0.99)), and on the specific star formation rate. A single
tdep(H2) versus sSFR relation is able to fit both "normal" star-forming
galaxies in our COLD GASS sample, as well as more extreme starburst galaxies
(LIRGs and ULIRGs), which have tdep(H2) < 10^8 yr. Normal galaxies at z=1-2 are
displaced with respect to the local galaxy population in the tdep(H2) versus
sSFR plane and have molecular gas depletion times that are a factor of 3-5
times longer at a given value of sSFR due to their significantly larger gas
fractions.Comment: Accepted for publication in MNRAS. 19 pages, 11 figure
The impact of interactions, bars, bulges, and AGN on star formation efficiency in local massive galaxies
Using observations from the GASS and COLD GASS surveys and complementary data
from SDSS and GALEX, we investigate the nature of variations in gas depletion
time observed across the local massive galaxy population. The large and
unbiased COLD GASS sample allows us to assess the relative importance of galaxy
interactions, bar instabilities, morphologies and the presence of AGN in
regulating star formation efficiency. Both the H2 mass fraction and depletion
time vary as a function of the distance of a galaxy from the main sequence in
the SFR-M* plane. The longest gas depletion times are found in below-main
sequence bulge-dominated galaxies that are either gas-poor, or else on average
less efficient than disk-dominated galaxy at converting into stars any cold gas
they may have. We find no link between AGN and these long depletion times. The
galaxies undergoing mergers or showing signs of morphological disruptions have
the shortest molecular gas depletion times, while those hosting strong stellar
bars have only marginally higher global star formation efficiencies as compared
to matched control samples. Our interpretation is that depletion time
variations are caused by changes in the ratio between the gas mass traced by
the CO(1-0) observations, and the gas mass in high density star-forming cores,
with interactions, mergers and bar instabilities able to locally increase
pressure and raise the ratio of efficiently star-forming gas to CO-detected
gas. Building a sample representative of the local massive galaxy population,
we derive a global Kennicutt-Schmidt relation of slope 1.18+/-0.24, and observe
structure within the scatter around this relation, with galaxies having low
(high) stellar mass surface densities lying systematically above (below) the
mean relation, suggesting that gas surface density is not the only parameter
driving the global star formation ability of a galaxy.Comment: 19 pages, 12 figures, accepted for publication in Ap
Gas Inflow in Barred Galaxies - Effects of Secondary Bars
We report here results of high-resolution hydrodynamical simulations of gas
flows in barred galaxies, with a focus on gas dynamics in the central
kiloparsec. In a single bar with an Inner Lindblad Resonance, we find either
near-circular motion of gas in the nuclear ring, or a spiral shock extending
towards the galaxy center, depending on the sound speed in the gas. From a
simple model of a dynamically-possible doubly barred galaxy with resonant
coupling, we infer that the secondary bar is likely to end well inside its
corotation. Such a bar cannot create shocks in the gas flow, and therefore will
not reveal itself in color maps through straight dust lanes: the gas flows
induced by it are different from those caused by the rapidly rotating main
bars. In particular, we find that secondary stellar bars are unlikely to
increase the mass inflow rate into the galactic nucleus.Comment: Accepted for publication in MNRAS, 12 pages, 5 figures. Because of
space limitations, Fig.5 has low resolution in the paper. For better quality,
see http://www-thphys.physics.ox.ac.uk/users/WitoldMaciejewski/pub.htm
Recommended from our members
IL2RA Genetic Heterogeneity in Multiple Sclerosis and Type 1 Diabetes Susceptibility and Soluble Interleukin-2 Receptor Production
Multiple sclerosis (MS) and type 1 diabetes (T1D) are organ-specific autoimmune disorders with significant heritability, part of which is conferred by shared alleles. For decades, the Human Leukocyte Antigen (HLA) complex was the only known susceptibility locus for both T1D and MS, but loci outside the HLA complex harboring risk alleles have been discovered and fully replicated. A genome-wide association scan for MS risk genes and candidate gene association studies have previously described the IL2RA gene region as a shared autoimmune locus. In order to investigate whether autoimmunity risk at IL2RA was due to distinct or shared alleles, we performed a genetic association study of three IL2RA variants in a DNA collection of up to 9,407 healthy controls, 2,420 MS, and 6,425 T1D subjects as well as 1,303 MS parent/child trios. Here, we report “allelic heterogeneity” at the IL2RA region between MS and T1D. We observe an allele associated with susceptibility to one disease and risk to the other, an allele that confers susceptibility to both diseases, and an allele that may only confer susceptibility to T1D. In addition, we tested the levels of soluble interleukin-2 receptor (sIL-2RA) in the serum from up to 69 healthy control subjects, 285 MS, and 1,317 T1D subjects. We demonstrate that multiple variants independently correlate with sIL-2RA levels
Thrive: Success Strategies for the Modern-Day Faculty Member
The THRIVE collection is intended to help faculty thrive in their roles as educators, scholars, researchers, and clinicians. Each section contains a variety of thought-provoking topics that are designed to be easily digested, guide personal reflection, and put into action. Please use the THRIVE collection to help: Individuals study topics on their own, whenever and wherever they want Peer-mentoring or other learning communities study topics in small groups Leaders and planners strategically insert faculty development into existing meetings
Faculty identify campus experts for additional learning, grand rounds, etc. If you have questions or want additional information on a topic, simply contact the article author or email [email protected]://digitalcommons.unmc.edu/facdev_books/1000/thumbnail.jp
Training attention control of very preterm infants: protocol for a feasibility study of the Attention Control Training (ACT)
Background
Children born preterm may display cognitive, learning, and behaviour difficulties as they grow up. In particular, very premature birth (gestation age between 28 and less than 32 weeks) may put infants at increased risk of intellectual deficits and attention deficit disorder. Evidence suggests that the basis of these problems may lie in difficulties in the development of executive functions. One of the earliest executive functions to emerge around 1 year of age is the ability to control attention. An eye-tracking-based cognitive training programme to support this emerging ability, the Attention Control Training (ACT), has been developed and tested with typically developing infants. The aim of this study is to investigate the feasibility of using the ACT with healthy very preterm (VP) infants when they are 12 months of age (corrected age). The ACT has the potential to address the need for supporting emerging cognitive abilities of VP infants with an early intervention, which may capitalise on infants’ neural plasticity.
Methods/design
The feasibility study is designed to investigate whether it is possible to recruit and retain VP infants and their families in a randomised trial that compares attention and social attention of trained infants against those that are exposed to a control procedure. Feasibility issues include the referral/recruitment pathway, attendance, and engagement with testing and training sessions, completion of tasks, retention in the study, acceptability of outcome measures, quality of data collected (particularly, eye-tracking data). The results of the study will inform the development of a larger randomised trial.
Discussion
Several lines of evidence emphasise the need to support emerging cognitive and learning abilities of preterm infants using early interventions. However, early interventions with preterm infants, and particularly very preterm ones, face difficulties in recruiting and retaining participants. These problems are also augmented by the health vulnerability of this population. This feasibility study will provide the basis for informing the implementation of an early cognitive intervention for very preterm infants.
Trial registration
Registered Registration ID: NCT03896490. Retrospectively registered at Clinical Trials Protocol Registration and Results System (clinicaltrials.gov)
Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome
Study Question What is the recommended assessment and management of women with polycystic ovary syndrome (PCOS), based on the best available evidence, clinical expertise, and consumer preference? Summary Answer International evidence-based guidelines including 166 recommendations and practice points, addressed prioritized questions to promote consistent, evidence-based care and improve the experience and health outcomes of women with PCOS. What Is Known Already Previous guidelines either lacked rigorous evidence-based processes, did not engage consumer and international multidisciplinary perspectives, or were outdated. Diagnosis of PCOS remains controversial and assessment and management are inconsistent. The needs of women with PCOS are not being adequately met and evidence practice gaps persist. Study Design, Size, Duration International evidence-based guideline development engaged professional societies and consumer organizations with multidisciplinary experts and women with PCOS directly involved at all stages. Appraisal of Guidelines for Research and Evaluation (AGREE) II-compliant processes were followed, with extensive evidence synthesis. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework was applied across evidence quality, feasibility, acceptability, cost, implementation and ultimately recommendation strength. Participants/Materials, Setting, Methods Governance included a six continent international advisory and a project board, five guideline development groups, and consumer and translation committees. Extensive health professional and consumer engagement informed guideline scope and priorities. Engaged international society-nominated panels included pediatrics, endocrinology, gynecology, primary care, reproductive endocrinology, obstetrics, psychiatry, psychology, dietetics, exercise physiology, public health and other experts, alongside consumers, project management, evidence synthesis, and translation experts. Thirty-seven societies and organizations covering 71 countries engaged in the process. Twenty face-to-face meetings over 15 months addressed 60 prioritized clinical questions involving 40 systematic and 20 narrative reviews. Evidence-based recommendations were developed and approved via consensus voting within the five guideline panels, modified based on international feedback and peer review, with final recommendations approved across all panels. Main Results and the Role of Chance The evidence in the assessment and management of PCOS is generally of low to moderate quality. The guideline provides 31 evidence based recommendations, 59 clinical consensus recommendations and 76 clinical practice points all related to assessment and management of PCOS. Key changes in this guideline include: i) considerable refinement of individual diagnostic criteria with a focus on improving accuracy of diagnosis; ii) reducing unnecessary testing; iii) increasing focus on education, lifestyle modification, emotional wellbeing and quality of life; and iv) emphasizing evidence based medical therapy and cheaper and safer fertility management. Limitations, Reasons for Caution Overall evidence is generally low to moderate quality, requiring significantly greater research in this neglected, yet common condition, especially around refining specific diagnostic features in PCOS. Regional health system variation is acknowledged and a process for guideline and translation resource adaptation is provided. Wider Implications of the Findings The international guideline for the assessment and management of PCOS provides clinicians with clear advice on best practice based on the best available evidence, expert multidisciplinary input and consumer preferences. Research recommendations have been generated and a comprehensive multifaceted dissemination and translation program supports the guideline with an integrated evaluation program. Study Funding/Competing Interest(S) The guideline was primarily funded by the Australian National Health and Medical Research Council of Australia (NHMRC) supported by a partnership with ESHRE and the American Society for Reproductive Medicine. Guideline development group members did not receive payment. Travel expenses were covered by the sponsoring organizations. Disclosures of conflicts of interest were declared at the outset and updated throughout the guideline process, aligned with NHMRC guideline processes. Full details of conflicts declared across the guideline development groups are available at https://www.monash.edu/medicine/sphpm/mchri/pcos/guideline in the Register of disclosures of interest. Of named authors, Dr Costello has declared shares in Virtus Health and past sponsorship from Merck Serono for conference presentations. Prof. Laven declared grants from Ferring, Euroscreen and personal fees from Ferring, Euroscreen, Danone and Titus Healthcare. Prof. Norman has declared a minor shareholder interest in an IVF unit. The remaining authors have no conflicts of interest to declare. The guideline was peer reviewed by special interest groups across our partner and collaborating societies and consumer organizations, was independently assessed against AGREEII criteria and underwent methodological review. This guideline was approved by all members of the guideline development groups and was submitted for final approval by the NHMRC
Los servicios en los esquemas de integración: algunas consideraciones y opciones para Centroamérica: versión provisional
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