We present the results of the first, deep ALMA imaging covering the full 4.5 sq arcmin of the Hubble Ultra Deep Field (HUDF) as previously imaged with WFC3/IR on HST. Using a mosaic of 45 pointings, ...we have obtained a homogeneous 1.3mm image of the HUDF, achieving an rms sensitivity of 35 microJy, at a resolution of 0.7 arcsec. From an initial list of ~50 >3.5sigma peaks, a rigorous analysis confirms 16 sources with flux densities S(1.3) > 120 microJy. All of these have secure galaxy counterparts with robust redshifts ( = 2.15), and 12 are also detected at 6GHz in new deep JVLA imaging. Due to the wealth of supporting data in this unique field, the physical properties of the ALMA sources are well constrained, including their stellar masses (M*) and UV+FIR star-formation rates (SFR). Our results show that stellar mass is the best predictor of SFR in the high-z Universe; indeed at z > 2 our ALMA sample contains 7 of the 9 galaxies in the HUDF with M* > 2 x 10^10 Msun and we detect only one galaxy at z > 3.5, reflecting the rapid drop-off of high-mass galaxies with increasing redshift. The detections, coupled with stacking, allow us to probe the redshift/mass distribution of the 1.3-mm background down to S(1.3) ~ 10 micro-Jy. We find strong evidence for a steep `main sequence' for star-forming galaxies at z ~ 2, with SFR \propto M* and a mean specific SFR = 2.2 /Gyr. Moreover, we find that ~85% of total star formation at z ~ 2 is enshrouded in dust, with ~65% of all star formation at this epoch occurring in high-mass galaxies (M* > 2 x 10^10 Msun), for which the average obscured:unobscured SF ratio is ~200. Finally, we combine our new ALMA results with the existing HST data to revisit the cosmic evolution of star-formation rate density; we find that this peaks at z ~ 2.5, and that the star-forming Universe transits from primarily unobscured to primarily obscured thereafter at z ~ 4.
SN 2008D was discovered while following up an unusually bright X-ray transient in the nearby spiral galaxy NGC 2770. We present early optical spectra (obtained 1.75 days after the X-ray transient) ...which allowed the first identification of the object as a supernova at redshift z = 0.007. These spectra were acquired during the initial declining phase of the light curve, likely produced in the stellar envelope cooling after shock breakout, and rarely observed. They exhibit a rather flat spectral energy distribution with broad undulations, and a strong, W-shaped feature with minima at 3980 and 4190 AA (rest frame). We also present extensive spectroscopy and photometry of the supernova during the subsequent photospheric phase. Unlike supernovae associated with gamma-ray bursts, SN 2008D displayed prominent He features and is therefore of Type Ib.
Ly-alpha blobs (LABs) offer insight into the complex interface between galaxies and their circumgalactic medium. Whilst some LABs have been found to contain luminous star-forming galaxies and active ...galactic nuclei that could potentially power the Ly-alpha emission, others appear not to be associated with obvious luminous galaxy counterparts. It has been speculated that LABs may be powered by cold gas streaming on to a central galaxy, providing an opportunity to directly observe the `cold accretion' mode of galaxy growth. Star-forming galaxies in LABs could be dust obscured and therefore detectable only at longer wavelengths. We stack deep SCUBA-2 observations of the SSA22 field to determine the average 850um flux density of 34 LABs. We measure S_850 = 0.6 +/- 0.2mJy for all LABs, but stacking the LABs by size indicates that only the largest third (area > 1794 kpc^2) have a mean detection, at 4.5 sigma, with S_850 = 1.4 +/- 0.3mJy. Only two LABs (1 and 18) have individual SCUBA-2 > 3.5 sigma detections at a depth of 1.1mJy/beam. We consider two possible mechanisms for powering the LABs and find that central star formation is likely to dominate the emission of Ly-alpha, with cold accretion playing a secondary role.
Abstract
The AKT/mTOR pathway is frequently hyperactivated in T-cell acute lymphoblastic leukemia (T-ALL). To model inhibition of this pathway in lymphoma, mice with T-lymphocyte-specific, ...constitutively active AKT (Lck-MyrAkt2) were crossed to mice with genetically reduced mTOR expression (knock-down, KD). Mice with genetic reduction of mTOR had increased survival by 10 weeks relative to wild type mTOR mice, though both developed thymic pre-T-cell lymphoblastic leukemia/lymphoma (pre-T LBL). Similarly, when mTOR wild type Lck-MyrAkt2 mice were treated for 8 weeks with the rapamycin analog, everolimus, an inhibitor of the mTOR TORC1 complex, survival was also increased. Gene expression profiling of thymic lymphomas from the mice revealed that mTOR KD was associated with decreased expression of Cdk6, a critical proliferative control node in T-cell development and oncogenic transformation. Pharmacologic inhibition of mTOR in tumor cells also decreased CDK6. The combination of a mTOR inhibitor (rapamycin) and a CDK4/6 inhibitor (PD-0332991, Palbociclib) synergistically decreased the overall viability and signaling downstream of drug targets in mouse lymphoma cells and in human T-ALL/LBL cell lines. This combination was also evaluated in mice using a disseminated leukemia model. In vivo treatment with this combination not only reduced tumor size by inhibiting tumor cell proliferation and arresting tumor cell cycle, but also increased overall survival. We are currently validating upstream regulators of Cdk6 as well as downstream targets in the pre-T LBL tumors from the mTOR deficient mice.
Citation Format: Shuling Zhang, Joy M. Gary, John K. Simmons, Jinfei Xu, Benjamin J. Gamache, Ke Zhang, Nicholas Watson, Alexander L. Kovalchuk, Aleksandra M. Michalowski, Jin-Qiu Chen, Michelle A. Herrmann, Tuddow Thaiwong, Matti Kiupel, Wendy Dubois, Joseph R. Testa, Beverly A. Mock. Genetic and pharmacologic inhibition of mTOR delays mortality due to thymc lymphoma formation in mice and is associated with decreases in cell cycle proteins. abstract. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2833.
We present \(\simeq\)0\(.\!\!^{\prime\prime}4\)-resolution extinction-independent distributions of star formation and dust in 11 star-forming galaxies (SFGs) at \(z = 1.3-3.0\). These galaxies are ...selected from sensitive, blank-field surveys of the \(2' \times 2'\) Hubble Ultra-Deep Field at \(\lambda = 5\) cm and 1.3 mm using the Karl G. Jansky Very Large Array (VLA) and Atacama Large Millimeter/submillimeter Array (ALMA). They have star-formation rates (SFRs), stellar masses, and dust properties representative of massive main-sequence SFGs at \(z \sim 2\). Morphological classification performed on spatially-resolved stellar mass maps indicates a mixture of disk and morphologically disturbed systems; half of the sample harbor X-ray active galactic nuclei (AGN), thereby representing a diversity of \(z \sim 2\) SFGs undergoing vigorous mass assembly. We find that their intense star formation most frequently occurs at the location of stellar-mass concentration and extends over an area comparable to their stellar-mass distribution, with a median diameter of \(4.2 \pm 1.8\) kpc. This provides direct evidence for galaxy-wide star formation in distant, blank-field-selected main-sequence SFGs. The typical galactic-average SFR surface density is 2.5 M\(_{\odot}\)yr\(^{-1}\)kpc\(^{-2}\), sufficiently high to drive outflows. In X-ray-selected AGN where radio emission is enhanced over the level associated with star formation, the radio excess pinpoints the AGN, which are found to be co-spatial with star formation. The median extinction-independent size of main-sequence SFGs is two times larger than those of bright submillimeter galaxies whose SFRs are \(3-8\) times larger, providing a constraint on the characteristic SFR (\(\sim300\) M\(_{\odot}\)yr\(^{-1}\)) above which a significant population of more compact star-forming galaxies appears to emerge.
Background
Strategies to mitigate the impact of COVID‐19 in special populations are complex and challenging. Few studies have addressed the impact of COVID‐19 on pediatric patients with cancer in ...low‐ and middle‐income countries.
Methods
Multicenter observational cohort study with prospective records and retrospective analyses starting in April 2020 in 21 pediatric oncology centers distributed throughout Brazil. Participants: Patients under 18 years of age who are infected by the SARS‐CoV‐2 virus (confirmed diagnosis through reverse transcriptase‐polymerase chain reaction RT‐PCR) while under treatment at pediatric oncology centers. The variables of interest included clinical symptoms, diagnostic and therapeutic measures. The repercussions of SARS‐CoV‐2 infection on cancer treatment and general prognosis were monitored.
Results
One hundred seventy‐nine patients were included (median age 6 4–13 years, 58% male). Of these, 55.9% had acute leukemia and 34.1% had solid tumors. The presence of SARS‐CoV‐2 was diagnosed by RT‐PCR. Various laboratory markers were analyzed, but showed no correlation with outcome. Children with low or high BMI for age had lower overall survival (71.4% and 82.6%, respectively) than those with age‐appropriate BMI (92.7%) (p = .007). The severity of presentation at diagnosis was significantly associated with outcome (p < .001). Overall mortality in the presence of infection was 12.3% (n = 22).
Conclusion
In children with cancer and COVID‐19, lower BMI was associated with worse prognosis. The mortality in this group of patients (12.3%) was significantly higher than that described in the pediatric population overall (∼1%).
We investigate the properties of the galaxies selected from the deepest 850-micron survey undertaken to date with SCUBA-2 on the JCMT. This deep 850-micron imaging was taken in parallel with deep ...450-micron imaging in the very best observing conditions as part of the SCUBA-2 Cosmology Legacy Survey. A total of 106 sources were uncovered at 850 microns from ~150, sq. arcmin in the centre of the COSMOS/UltraVISTA/CANDELS field, imaged to a typical rms depth of ~0.25 mJy. We utilise the wealth of available deep multi-frequency data to establish the complete redshift distribution for this sample, yielding = 2.38 +- 0.09, a mean redshift comparable with that derived for all but the brightest previous sub-mm samples. We have also been able to establish the stellar masses of the majority of the galaxy identifications, enabling us to explore their location on the star-formation-rate:stellar-mass (SFR:M*) plane. Crucially, our new deep sample reaches flux densities equivalent to SFR ~ 100 Msun/yr, enabling us to confirm that sub-mm galaxies form the high-mass end of the `main sequence' (MS) of star-forming galaxies at z > 1.5 (with a mean specific SFR of sSFR = 2.25 +- 0.19 /Gyr at z ~ 2.5). Our results are consistent with no significant flattening of the MS towards high masses at these redshifts, suggesting that reports of such flattening possibly arise from under-estimates of dust-enshrouded star-formation activity in massive star-forming galaxies. However, our findings add to the growing evidence that average sSFR rises only slowly at high redshift, resulting in log(sSFR) being an apparently simple linear function of the age of the Universe.
This paper introduces EGG, the Empirical Galaxy Generator, a tool designed within the ASTRODEEP collaboration to generate mock galaxy catalogs for deep fields with realistic fluxes and simple ...morphologies. The simulation procedure is based exclusively on empirical prescriptions -- rather than first principles -- to provide the most accurate match with observations at 0<z<7. In particular, we consider that galaxies can be either quiescent or star-forming, and use their stellar mass (M*) and redshift (z) as the fundamental properties from which all the other observables can be statistically derived. Drawing z and M* from the observed galaxy stellar mass functions, we associate a star formation rate (SFR) to each galaxy from the tight SFR-M* main sequence, while dust attenuation, optical colors and morphologies (including bulge-to-total ratios, sizes and aspect ratios) are obtained from empirical relations that we establish from the high quality Hubble and Herschel observations available in the CANDELS fields. Random scatter is introduced in each step to reproduce the observed distributions of each parameter. Based on these observables, a panchromatic spectral energy distribution (SED) is selected for each galaxy and synthetic photometry is produced by integrating the redshifted SED in common broad-band filters. Finally, the mock galaxies are placed on the sky at random positions with a fixed angular two-point correlation function to implement basic clustering. The resulting flux catalogs reproduce accurately the observed number counts in all broad bands from the ultraviolet up to the sub-millimeter, and can be directly fed to image simulators such as Skymaker. The images can then be used to test source extraction softwares and image-based techniques such as stacking. EGG is open-source, and is made available to the community together with a set of pre-generated catalogs and images.
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