Abstract Background Despite increasing interest in advance care planning (ACP) and prior ACP descriptions, a consensus definition does not yet exist to guide clinical, research, and policy ...initiatives. Objective To develop a consensus definition of ACP for adults. Design Delphi Panel Setting/Participants Participants included a multidisciplinary panel of international ACP experts consisting of 52 clinicians, researchers, and policy leaders from 4 countries, and a patient/surrogate advisory committee. Measurements We conducted 10 rounds of a modified Delphi method and qualitatively analyzed panelists’ input. Panelists identified several themes lacking consensus, and iteratively discussed and developed a final consensus definition. Results Panelists identified several tensions concerning ACP concepts such as whether the definition should focus on conversations vs. written advance directives; patients’ values vs. treatment preferences; current shared decision making vs. future medical decisions; and who should be included in the process. The panel achieved a final consensus one-sentence definition and accompanying goals statement: “Advance care planning is a process that supports adults at any age or stage of health in understanding and sharing their personal values, life goals, and preferences regarding future medical care. The goal of advance care planning is to help ensure that people receive medical care that is consistent with their values, goals and preferences during serious and chronic illness.” The panel also described strategies to best support adults in ACP. Conclusions A multidisciplinary Delphi panel developed a consensus definition for ACP for adults that can be used to inform implementation and measurement of ACP clinical, research, and policy initiatives.
We present 3, 15, and 33 GHz imaging toward galaxy nuclei and extranuclear star-forming regions using the Karl G. Jansky Very Large Array as part of the Star Formation in Radio Survey. With 3-33 GHz ...radio spectra, we measured the spectral indices and corresponding thermal (free-free) emission fractions for a sample of 335 discrete regions having significant detections in at least two radio bands. After removing 14 likely background galaxies, we find that the median thermal fraction at 33 GHz is 92% 0.8% with a median absolute deviation of 11%, when a two-component power-law model is adopted to fit the radio spectrum. Limiting the sample to 238 sources that are confidently identified as star-forming regions and not affected by potential AGN contamination (i.e., having galactocentric radii rG ≥ 250 pc) results in a median thermal fraction of 93% 0.8% with a median absolute deviation of 10%. We further measure the thermal fraction at 33 GHz for 163 regions identified at 7″ resolution to be 94% 0.8% with a median absolute deviation of 8%. Together, these results confirm that free-free emission dominates the radio spectra of star-forming regions on scales up to ∼500 pc in normal star-forming galaxies. We additionally find a factor of ∼1.6 increase in the scatter of the measured spectral index and thermal fraction distributions as a function of decreasing galactocentric radius. This trend is likely reflective of the continuous star formation activity occurring in the galaxy centers, resulting in a larger contribution of diffuse nonthermal emission relative to star-forming regions in the disk.
Gas clouds in present-day galaxies are inefficient at forming stars. Low star-formation efficiency is a critical parameter in galaxy evolution: it is why stars are still forming nearly 14 billion ...years after the Big Bang and why star clusters generally do not survive their births, instead dispersing to form galactic disks or bulges. Yet the existence of ancient massive bound star clusters (globular clusters) in the Milky Way suggests that efficiencies were higher when they formed ten billion years ago. A local dwarf galaxy, NGC 5253, has a young star cluster that provides an example of highly efficient star formation. Here we report the detection of the J = 3→2 rotational transition of CO at the location of the massive cluster. The gas cloud is hot, dense, quiescent and extremely dusty. Its gas-to-dust ratio is lower than the Galactic value, which we attribute to dust enrichment by the embedded star cluster. Its star-formation efficiency exceeds 50 per cent, tenfold that of clouds in the Milky Way. We suggest that high efficiency results from the force-feeding of star formation by a streamer of gas falling into the galaxy.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
High critical density molecular lines like HCN (1-0) or HCO+ (1-0) represent our best tool to study currently star-forming, dense molecular gas at extragalactic distances. The optical depth ...of these lines is a key ingredient to estimate the effective density required to excite emission. However, constraints on this quantity are even scarcer in the literature than measurements of the high-density tracers themselves. Here, we combine new observations of HCN, HCO+ and HNC (1-0) and their optically thin isotopologues H13CN, H13CO+ and HN13C (1-0) to measure isotopologue line ratios. We use IRAM 30-m observations from the large programme EMPIRE and new Atacama Large Millimetre/submillimetre Array observations, which together target six nearby star-forming galaxies. Using spectral stacking techniques, we calculate or place strong upper limits on the HCN/H13CN, HCO+/H13CO+ and HNC/HN13C line ratios in the inner parts of these galaxies. Under simple assumptions, we use these to estimate the optical depths of HCN (1-0) and HCO+ (1-0) to be τ ∼ 2–11 in the active, inner regions of our targets. The critical densities are consequently lowered to values between 5 and 20 × 105 cm−3, 1 and 3 × 105 cm−3 and 9 × 104 cm−3 for HCN, HCO+ and HNC, respectively. We study the impact of having different beam-filling factors, η, on these estimates and find that the effective critical densities decrease by a factor of
$\frac{\eta _{12}}{\eta _{13}}\,\tau _{12}$
. A comparison to existing work in NGC 5194 and NGC 253 shows the HCN/H13CN and HCO+/H13CO+ ratios in agreement with our measurements within the uncertainties. The same is true for studies in other environments such as the Galactic Centre or nuclear regions of active galactic nucleus dominated nearby galaxies.
We present 33 GHz imaging for 112 pointings toward galaxy nuclei and extranuclear star-forming regions at 2″ resolution using the Karl G. Jansky Very Large Array (VLA) as part of the Star Formation ...in Radio Survey. A comparison with 33 GHz Robert C. Byrd Green Bank Telescope single-dish observations indicates that the interferometric VLA observations recover 78% 4% of the total flux density over 25″ regions ( kpc scales) among all fields. On these scales, the emission being resolved out is most likely diffuse non-thermal synchrotron emission. Consequently, on the 30-300 pc scales sampled by our VLA observations, the bulk of the 33 GHz emission is recovered and primarily powered by free-free emission from discrete H ii regions, making it an excellent tracer of massive star formation. Of the 225 discrete regions used for aperture photometry, 162 are extranuclear (i.e., having galactocentric radii rG ≥ 250 pc) and detected at >3 significance at 33 GHz and in H . Assuming a typical 33 GHz thermal fraction of 90%, the ratio of optically-thin 33 GHz to uncorrected H star formation rates indicates a median extinction value on 30-300 pc scales of AH 1.26 0.09 mag, with an associated median absolute deviation of 0.87 mag. We find that 10% of these sources are "highly embedded" (i.e., AH 3.3 mag), suggesting that on average, H ii regions remain embedded for 1 Myr. Finally, we find the median 33 GHz continuum-to-H line flux ratio to be statistically larger within rG < 250 pc relative to the outer disk regions by a factor of 1.82 0.39, while the ratio of 33 GHz to 24 m flux densities is lower by a factor of 0.45 0.08, which may suggest increased extinction in the central regions.
Abstract
We present new 3 mm observations of the ionized gas toward the nuclear starburst in the nearby (
D
∼ 3.5 Mpc) galaxy NGC 253. With ALMA, we detect emission from the H40
α
and He40
α
lines in ...the central 200 pc of this galaxy on spatial scales of ∼4 pc. The recombination line emission primarily originates from a population of approximately a dozen embedded super star clusters in the early stages of formation. We find that emission from these clusters is characterized by electron temperatures ranging from 7000 to 10,000 K and measures an average singly ionized helium abundance 〈
Y
+
〉 = 0.25 ± 0.06, both of which are consistent with values measured for H
ii
regions in the center of the Milky Way. We also report the discovery of unusually broad line width recombination line emission originating from seven of the embedded clusters. We suggest that these clusters contribute to the launching of the large-scale hot wind observed to emanate from the central starburst. Finally, we use the measured recombination line fluxes to improve the characterization of overall embedded cluster properties, including the distribution of cluster masses and the fractional contribution of the clustered star formation to the total starburst, which we estimate is at least 50%.
We present Very Large Array observations of the 33 GHz radio continuum emission from 22 local ultraluminous and luminous infrared (IR) galaxies (U/LIRGs). These observations have spatial (angular) ...resolutions of 30-720 pc (0 07-0 67) in a part of the spectrum that is likely to be optically thin. This allows us to estimate the size of the energetically dominant regions. We find half-light radii from 30 pc to 1.7 kpc. The 33 GHz flux density correlates well with the IR emission, and we take these sizes as indicative of the size of the region that produces most of the energy. Combining our 33 GHz sizes with unresolved measurements, we estimate the IR luminosity and star formation rate per area and the molecular gas surface and volume densities. These quantities span a wide range (4 dex) and include some of the highest values measured for any galaxy (e.g., ). At least 13 sources appear Compton thick ( ). Consistent with previous work, contrasting these data with observations of normal disk galaxies suggests a nonlinear and likely multivalued relation between star formation rate and molecular gas surface density, though this result depends on the adopted CO-to-H2 conversion factor and the assumption that our 33 GHz sizes apply to the gas. Eleven sources appear to exceed the luminosity surface density predicted for starbursts supported by radiation pressure and supernova feedback; however, we note the need for more detailed observations of the inner disk structure. U/LIRGs with higher surface brightness exhibit stronger C ii 158 m deficits, consistent with the suggestion that high energy densities drive this phenomenon.
Context. Observations of chemical species can provide insights into the physical conditions of the emitting gas however it is important to understand how their abundances and excitation vary within ...different heating environments. C2H is a molecule typically found in PDR regions of our own Galaxy but there is evidence to suggest it also traces other regions undergoing energetic processing in extragalactic environments. Aims. As part of the ALCHEMI ALMA large program, we map the emission of C2H in the central molecular zone of the nearby starburst galaxy NGC 253 at 1.6″ (28 pc) resolution and characterize it to understand its chemical origins. Methods. We used spectral modeling of the N = 1−0 through N = 4−3 rotational transitions of C2H to derive the C2H column densities towards the dense clouds in NGC 253. We then use chemical modeling, including photodissociation region (PDR), dense cloud, and shock models to investigate the chemical processes and physical conditions that are producing the molecular emission. Results. We find high C2H column densities of ∼1015 cm−2 detected towards the dense regions of NGC 253. We further find that these column densities cannot be reproduced if it is assumed that the emission arises from the PDR regions at the edge of the clouds. Instead, we find that the C2H abundance remains high even in the high visual extinction interior of these clouds and that this is most likely caused by a high cosmic-ray ionization rate.
We present new Karl G. Jansky Very Large Array radio continuum images of the nuclei of Arp 220, the nearest ultra-luminous infrared galaxy. These new images have both the angular resolution to study ...the detailed morphologies of the two nuclei that power the galaxy merger and sensitivity to a wide range of spatial scales. At 33 GHz, we achieve a resolution of 0.081 x 0.063 and resolve the radio emission surrounding both nuclei. We conclude from the decomposition of the radio spectral energy distribution that a majority of the 33 GHz emission is synchrotron radiation. The spatial distributions of radio emission in both nuclei are well described by exponential profiles. According to the calculations, the nuclei of Arp 220 are only transparent in the frequency range ~5-350 GHz. Our results offer no clear evidence that an active galactic nucleus dominates the emission from either nucleus at 33 GHz.
Introduction
Alzheimer's disease (AD) is characterized by neurotoxic immuno‐inflammation concomitant with cytotoxic oligomerization of amyloid beta (Aβ) and tau, culminating in concurrent, ...interdependent immunopathic and proteopathic pathogeneses.
Methods
We performed a comprehensive series of in silico, in vitro, and in vivo studies explicitly evaluating the atomistic–molecular mechanisms of cytokine‐mediated and Aβ‐mediated neurotoxicities in AD. Next, 471 new chemical entities were designed and synthesized to probe the pathways identified by these molecular mechanism studies and to provide prototypic starting points in the development of small‐molecule therapeutics for AD.
Results
In response to various stimuli (e.g., infection, trauma, ischemia, air pollution, depression), Aβ is released as an early responder immunopeptide triggering an innate immunity cascade in which Aβ exhibits both immunomodulatory and antimicrobial properties (whether bacteria are present, or not), resulting in a misdirected attack upon “self” neurons, arising from analogous electronegative surface topologies between neurons and bacteria, and rendering them similarly susceptible to membrane‐penetrating attack by antimicrobial peptides (AMPs) such as Aβ. After this self‐attack, the resulting necrotic (but not apoptotic) neuronal breakdown products diffuse to adjacent neurons eliciting further release of Aβ, leading to a chronic self‐perpetuating autoimmune cycle. AD thus emerges as a brain‐centric autoimmune disorder of innate immunity. Based upon the hypothesis that autoimmune processes are susceptible to endogenous regulatory processes, a subsequent comprehensive screening program of 1137 small molecules normally present in human brain identified tryptophan metabolism as a regulator of brain innate immunity and a source of potential endogenous anti‐AD molecules capable of chemical modification into multi‐site therapeutic modulators targeting AD's complex immunopathic–proteopathic pathogenesis.
Discussion
Conceptualizing AD as an autoimmune disease, identifying endogenous regulators of this autoimmunity, and designing small molecule drug‐like analogues of these endogenous regulators represents a novel therapeutic approach for AD.
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