133 research outputs found
Two Remarkably Luminous Galaxy Candidates at Revealed by JWST
The first few hundred Myrs at mark the last major uncharted epoch in
the history of the Universe, where only a single galaxy (GNz11 at )
is currently spectroscopically confirmed. Here we present a search for luminous
galaxies with /NIRCam photometry spanning m and
covering 49 arcmin from the public Early Release Science programs
(CEERS and GLASS). Our most secure candidates are two
systems: GLASS-z13 and GLASS-z11. These galaxies display abrupt
mag breaks in their spectral energy distributions, consistent with complete
absorption of flux bluewards of Lyman- that is redshifted to
and . Lower redshift interlopers such as dusty
quiescent galaxies with strong Balmer breaks would be comfortably detected at
in multiple bands where instead we find no flux. From SED modeling
we infer that these galaxies have already built up solar masses in
stars over the Myrs after the Big Bang. The brightness of
these sources enable morphological constraints. Tantalizingly, GLASS-z11 shows
a clearly extended exponential light profile, potentially consistent with a
disk galaxy of kpc. These sources, if confirmed, join
GNz11 in defying number density forecasts for luminous galaxies based on
Schechter UV luminosity functions, which require a survey area
larger than we have studied here to find such luminous sources at such high
redshifts. They extend evidence from lower redshifts for little or no evolution
in the bright end of the UV luminosity function into the cosmic dawn epoch,
with implications for just how early these galaxies began forming. This, in
turn, suggests that future deep observations may identify relatively
bright galaxies to much earlier epochs than might have been anticipated.Comment: Submitted to ApJL. Figs. 1 and 2 summarize the candidates, Fig. 3
places the brightness of these systems in context, Fig. 4 shows the
morphology, Fig. 5 explores implications for the UVLF. Comments warmly
welcome
UNCOVER: Candidate Red Active Galactic Nuclei at 3<z<7 with JWST and ALMA
The James Webb Space Telescope (JWST) is revolutionizing our knowledge of
galaxies and their actively accreting black holes. Using the JWST Cycle 1
Treasury program Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of
Reionization (UNCOVER) in the lensing field Abell 2744, we report the
identification of a sample of little red dots at that
likely contain highly-reddened accreting supermassive black holes. Using a
NIRCam-only selection to F444W mag, we find 26 sources over the
arcmin field that are blue in F115WF200W (or for ), red in F200WF444W =
(), and are dominated by a point-source like
central component. Of the 20 sources with deep ALMA 1.2-mm coverage, none are
detected individually or in a stack. For the majority of the sample, SED fits
to the JWST+ALMA observations prefer models with hot dust rather than obscured
star-formation to reproduce the red NIRCam colors and ALMA 1.2-mm
non-detections. While compact dusty star formation can not be ruled out, the
combination of extremely small sizes ( pc after
correction for magnification), red rest-frame optical slopes, and hot dust can
by explained by reddened broad-line active galactic nuclei (AGNs). Our targets
have faint mag but inferred
bolometric luminosities of erg/s, reflecting
their obscured nature. If the candidates are confirmed as AGNs with upcoming
UNCOVER spectroscopy, then we have found an abundant population of reddened
luminous AGN that are at least ten times more numerous than UV-luminous AGN at
the same intrinsic bolometric luminosity.Comment: submitted to Ap
First spectroscopic observations of the galaxies that reionized the Universe
Low-mass galaxies in the early universe are believed to be the building
blocks of present-day galaxies. These fledgling systems likely played a pivotal
role in cosmic reionization, a major phase transition from neutral Hydrogen to
ionized plasma around 600-800 Myr after the Big Bang. However, these galaxies
have eluded comprehensive spectroscopic studies owing to their extreme
faintness. Here we report the first spectroscopic analysis of 8 ultra-faint
galaxies during the epoch of reionization with absolute magnitudes between
M to mag (down to 0.005 ). The
combination of ultra-deep NIRSpec (Near-Infrared Spectrograph) observations and
the strong gravitational lensing boost of Abell~2744 allow us to derive the
first spectroscopic constraints on the prevalence of faint galaxies and their
ionizing properties during the Universe's first billion years. We find that
faint galaxies are prodigious producers of ionizing photons with log(/ Hz erg) =, a factor of 4 larger than canonical
values. This means that the total rate of ionizing photons produced by galaxies
exceeds that needed for reionization, even for modest values of escape fraction
( =5%). These findings provide robust evidence that faint galaxies
were the main drivers of cosmic reionization at .Comment: 29 pages, 7 figures, 2 table
Linee guida sulla isotretinoina - consensus
Qualche anno addietro, si sparse la notizia che l'isotretinoina orale sarebbe stata ritirata dal commercio. In quel periodo fu pubblicato sugli Annales de Dermatologie un articolo scritto da un dermatologo francese preoccupato per quanto sarebbe successo a noi dermatologi, privati della isotretinoina orale, nella gestione dei pazienti con acne grave. Si prospettava un quadro di desolante ritorno al passato con \uec pazienti vittime di decisioni amministrative, scientificamente morto discutibili, prese con superficialit\ue0. Fortunatamente questo non accadde vista la infondatezza delle argomentazioni accusatorie avanzate. Da questa vicenda emerse la consapevolezza che alla base di quanto successo c'era una preoccupante disinformazione sulle caratteristiche del farmaco estesa ad ampie fasce di soggetti coinvolti nella gestione e nell'utilizzo del prodotto, medici di medicina generale, pediatri, farmacisti e pazienti. Alla luce di questo abbiamo sentito l'esigenza di colmare questa lacuna e di preparare una nota informativa, chiara e completa, sulle caratteristiche dell'isotretinoina orale.
Tale documento era diretto, con modalit\ue0 e contenuti opportunamente adattati, alle singole categorie sopra riportate. L'obiettivo finale era quello di evitare che, a pazienti effettivamente bisognosi di tale trattamento, esso fosse negato con motivazioni inconsistenti o per disinformazione. Il lavoro congiunto di un board di dermatologi, appartenenti alle Societ\ue0 pi\uf9 rappresentative della Dermatologia Italiana, ha portato alla definizione di due documenti informativi sull'isotretinoina orale. Il primo \ue8 indirizzato a medici di medicina generale, pediatri e farmacisti ed il secondo ai pazienti. \uc8 in programmazione per il prossimo futuro la preparazione di linee guida aggiornate sull'utilizzo del farmaco ad uso dei dermatologi
The impact of HIV/SRH service integration on workload: analysis from the Integra Initiative in two African settings.
BACKGROUND: There is growing interest in integration of HIV and sexual and reproductive health (SRH) services as a way to improve the efficiency of human resources (HR) for health in low- and middle-income countries. Although this is supported by a wealth of evidence on the acceptability and clinical effectiveness of service integration, there is little evidence on whether staff in general health services can easily absorb HIV services. METHODS: We conducted a descriptive analysis of HR integration through task shifting/sharing and staff workload in the context of the Integra Initiative - a large-scale five-year evaluation of HIV/SRH integration. We describe the level, characteristics and changes in HR integration in the context of wider efforts to integrate HIV/SRH, and explore the impact of HR integration on staff workload. RESULTS: Improvements in the range of services provided by staff (HR integration) were more likely to be achieved in facilities which also improved other elements of integration. While there was no overall relationship between integration and workload at the facility level, HIV/SRH integration may be most influential on staff workload for provider-initiated HIV testing and counselling (PITC) and postnatal care (PNC) services, particularly where HIV care and treatment services are being supported with extra SRH/HIV staffing. Our findings therefore suggest that there may be potential for further efficiency gains through integration, but overall the pace of improvement is slow. CONCLUSIONS: This descriptive analysis explores the effect of HIV/SRH integration on staff workload through economies of scale and scope in high- and medium-HIV prevalence settings. We find some evidence to suggest that there is potential to improve productivity through integration, but, at the same time, significant challenges are being faced, with the pace of productivity gain slow. We recommend that efforts to implement integration are assessed in the broader context of HR planning to ensure that neither staff nor patients are negatively impacted by integration policy
The 3D-HST Survey: <i>Hubble Space Telescope</i> WFC3/G141 Grism Spectra, Redshifts, and Emission Line Measurements for ~ 100,000 Galaxies
We present reduced data and data products from the 3D-HST survey, a 248-orbit Treasury program. The survey obtained WFC3 G141 grism spectroscopy in four of the five CANDELS fields: AEGIS, COSMOS, GOODS-S, and UDS, along with WFC3 imaging, parallel ACS G800L spectroscopy, and parallel imaging. In a previous paper, we presented photometric catalogs in these four fields and in GOODS-N, the fifth CANDELS field. Here we describe and present the WFC3 G141 spectroscopic data, again augmented with data from GO-1600 in GOODS-N (PI: B. Weiner). We developed software to automatically and optimally extract interlaced two-dimensional (2D) and one-dimensional (1D) spectra for all objects in the Skelton et al. (2014) photometric catalogs. The 2D spectra and the multi-band photometry were fit simultaneously to determine redshifts and emission line strengths, taking the morphology of the galaxies explicitly into account. The resulting catalog has redshifts and line strengths (where available) for 22,548 unique objects down to (79,609 unique objects down to ). Of these, 5459 galaxies are at and 9621 are at , where Hα falls in the G141 wavelength coverage. The typical redshift error for galaxies is , i.e., one native WFC3 pixel. The limit for emission line fluxes of point sources is erg . All 2D and 1D spectra, as well as redshifts, line fluxes, and other derived parameters, are publicly available
Cost-effectiveness and resource implications of aggressive action on tuberculosis in China, India, and South Africa: a combined analysis of nine models.
BACKGROUND: The post-2015 End TB Strategy sets global targets of reducing tuberculosis incidence by 50% and mortality by 75% by 2025. We aimed to assess resource requirements and cost-effectiveness of strategies to achieve these targets in China, India, and South Africa. METHODS: We examined intervention scenarios developed in consultation with country stakeholders, which scaled up existing interventions to high but feasible coverage by 2025. Nine independent modelling groups collaborated to estimate policy outcomes, and we estimated the cost of each scenario by synthesising service use estimates, empirical cost data, and expert opinion on implementation strategies. We estimated health effects (ie, disability-adjusted life-years averted) and resource implications for 2016-35, including patient-incurred costs. To assess resource requirements and cost-effectiveness, we compared scenarios with a base case representing continued current practice. FINDINGS: Incremental tuberculosis service costs differed by scenario and country, and in some cases they more than doubled existing funding needs. In general, expansion of tuberculosis services substantially reduced patient-incurred costs and, in India and China, produced net cost savings for most interventions under a societal perspective. In all three countries, expansion of access to care produced substantial health gains. Compared with current practice and conventional cost-effectiveness thresholds, most intervention approaches seemed highly cost-effective. INTERPRETATION: Expansion of tuberculosis services seems cost-effective for high-burden countries and could generate substantial health and economic benefits for patients, although substantial new funding would be required. Further work to determine the optimal intervention mix for each country is necessary. FUNDING: Bill & Melinda Gates Foundation
The MOSDEF survey:AGN multi-wavelength identification, selection biases and host galaxy properties
We present results from the MOSFIRE Deep Evolution Field (MOSDEF) survey on
the identification, selection biases, and host galaxy properties of 55 X-ray,
IR and optically-selected active galactic nuclei (AGN) at . We
obtain rest-frame optical spectra of galaxies and AGN and use the BPT diagram
to identify optical AGN. We examine the uniqueness and overlap of the AGN
identified at different wavelengths. There is a strong bias against identifying
AGN at any wavelength in low mass galaxies, and an additional bias against
identifying IR AGN in the most massive galaxies. AGN hosts span a wide range of
star formation rate (SFR), similar to inactive galaxies once stellar mass
selection effects are accounted for. However, we find (at
significance) that IR AGN are in less dusty galaxies with relatively higher SFR
and optical AGN in dusty galaxies with relatively lower SFR. X-ray AGN
selection does not display a bias with host galaxy SFR. These results are
consistent with those from larger studies at lower redshifts. Within
star-forming galaxies, once selection biases are accounted for, we find AGN in
galaxies with similar physical properties as inactive galaxies, with no
evidence for AGN activity in particular types of galaxies. This is consistent
with AGN being fueled stochastically in any star-forming host galaxy. We do not
detect a significant correlation between SFR and AGN luminosity for individual
AGN hosts, which may indicate the timescale difference between the growth of
galaxies and their supermassive black holes
Witnessing the Early Growth and Life Cycle of Galaxies with KMOS3D
Near-infrared integral field unit (IFU) spectrographs are powerful tools for investigating galaxy evolution. We report on our recently completed multi-year KMOS3D survey of Halpha, [NII] and [SII] line emission of galaxies at redshift z ~ 0.7 - 2.7 with the K-band Multi-Object Spectrograph (KMOS) at the Very Large Telescope (VLT). With deep observations of 745 targets spanning over two orders of magnitude in galaxy mass, five billion years of cosmic time, and all levels of star formation, KMOS3D provides an unparalleled population-wide census of spatially-resolved kinematics, star formation, outflows and nebular gas conditions. The dataset sheds new light on the physical mechanisms driving the early growth and lifecycle of galaxies, and provides a rich legacy for the astronomical community
Micrometre-long covalent organic fibres by photoinitiated chain-growth radical polymerization on an alkali-halide surface
On-surface polymerization is a promising technique to prepare organic functional nanomaterials that are challenging to synthesize in solution, but it is typically used on metal substrates, which play a catalytic role. Previous examples on insulating surfaces have involved intermediate self-assembled structures, which face high barriers to diffusion, or annealing to higher temperatures, which generally causes rapid dewetting and desorption of the monomers. Here we report the photoinitiated radical polymerization, initiated from a two-dimensional gas phase, of a dimaleimide monomer on an insulating KCl surface. Polymer fibres up to 1 μm long are formed through chain-like rather than step-like growth. Interactions between potassium cations and the dimaleimide’s oxygen atoms facilitate the propagation of the polymer fibres along a preferred axis of the substrate over long distances. Density functional theory calculations, non-contact atomic force microscopy imaging and manipulations at room temperature were used to explore the initiation and propagation processes, as well as the structure and stability of the resulting one-dimensional polymer fibres
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