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Local and low-redshift (z < 3) galaxies are known to broadly follow a bimodal distribution: actively star-forming galaxies with relatively stable star-formation rates and passive systems. These two populations are connected by galaxies in relatively slow transition. By contrast, theory predicts that star formation was stochastic at early cosmic times and in low-mass systems 1-4 . These galaxies transitioned rapidly between starburst episodes and phases of suppressed star formation, potentially even causing temporary quiescence-so-called mini-quenching events 5,6 . However, the regime of star-formation burstiness is observationally highly unconstrained. Directly observing mini-quenched galaxies in the primordial Universe is therefore of utmost importance to constrain models of galaxy formation and transformation 7,8 . Early quenched galaxies have been identified out to redshift z < 5 (refs.  9-12 ) and these are all found to be massive (M ⋆  > 10 10  M ⊙ ) and relatively old. Here we report a (mini-)quenched galaxy at z = 7.3, when the Universe was only 700 Myr old. The JWST/NIRSpec spectrum is very blue (U-V = 0.16 ± 0.03 mag) but exhibits a Balmer break and no nebular emission lines. The galaxy experienced a short starburst followed by rapid quenching; its stellar mass (4-6 × 10 8  M ⊙ ) falls in a range that is sensitive to various feedback mechanisms, which can result in perhaps only temporary quenching., (© 2024. The Author(s).)

Several theories have been proposed to describe the formation of black hole seeds in the early Universe and to explain the emergence of very massive black holes observed in the first thousand million years after the Big Bang 1-3 . Models consider different seeding and accretion scenarios 4-7 , which require the detection and characterization of black holes in the first few hundred million years after the Big Bang to be validated. Here we present an extensive analysis of the JWST-NIRSpec spectrum of GN-z11, an exceptionally luminous galaxy at z = 10.6, revealing the detection of the [NeIV]λ2423 and CII*λ1335 transitions (typical of active galactic nuclei), as well as semi-forbidden nebular lines tracing gas densities higher than 10 9  cm -3 , typical of the broad line region of active galactic nuclei. These spectral features indicate that GN-z11 hosts an accreting black hole. The spectrum also reveals a deep and blueshifted CIVλ1549 absorption trough, tracing an outflow with velocity 800-1,000 km s -1 , probably driven by the active galactic nucleus. Assuming local virial relations, we derive a black hole mass of log ( M BH / M ⊙ ) = 6.2 ± 0.3 , accreting at about five times the Eddington rate. These properties are consistent with both heavy seeds scenarios and scenarios considering intermediate and light seeds experiencing episodic super-Eddington phases. Our finding explains the high luminosity of GN-z11 and can also provide an explanation for its exceptionally high nitrogen abundance., (© 2024. The Author(s).)

Large dust reservoirs (up to approximately 10 8  M ⊙ ) have been detected 1-3 in galaxies out to redshift z ≃ 8, when the age of the Universe was only about 600 Myr. Generating substantial amounts of dust within such a short timescale has proven challenging for theories of dust formation 4,5 and has prompted the revision of the modelling of potential sites of dust production 6-8 , such as the atmospheres of asymptotic giant branch stars in low-metallicity environments, supernova ejecta and the accelerated growth of grains in the interstellar medium. However, degeneracies between different evolutionary pathways remain when the total dust mass of galaxies is the only available observable. Here we report observations of the 2,175 Å dust attenuation feature, which is well known in the Milky Way and galaxies at z ≲ 3 (refs. 9-11 ), in the near-infrared spectra of galaxies up to z ≃ 7, corresponding to the first billion years of cosmic time. The relatively short timescale implied for the formation of carbonaceous grains giving rise to this feature 12 suggests a rapid production process, possibly in Wolf-Rayet stars or supernova ejecta., (© 2023. The Author(s).)

The brains of aged and young Fischer rats were examined using a modified version of Cajal's gold chloride stain for astrocytes. A sizable loss of pyramidal cells and remarkably hypertrophic astrocytes were found in the hippocampus of the aged animals, while the astrocytic changes were not seen in other forebrain regions. Four major characteristics of the pattern of hippocampal astrogliosis were noted: (1) the astrocytes were often found to be grouped in clusters; (2) grouped astrocytes were commonly seen to have similarly oriented processes; (3) small blood vessels were more often stained in regions of pyramidal cell degeneration and astroglial hypertrophy; and (4) reactive astrocytes were in several instances found to be gathered on the "border" between deteriorated regions and healthier appearing areas. This pattern was interpreted to suggest that the astrocyte clusters may be analogous to senile plaques. Since the aged Fischer animals have previously been found to exhibit retention deficits, the possibility that the hippocampal pathology is related to impaired memory in these animals was raised.

Apudomas are uncommon neoplasms composed of neuroendocrine cells. They include carcinoid tumors, islet cell tumors, and small cell lung carcinoma. We found six cases of apudomas in a series of 1028 renal transplants from three medical centers (0.58%). One of these had been reported in 1976. The cases included a carcinoid tumor of a Meckel's diverticulum discovered and removed prior to transplantation, with no evidence of recurrence 9 years later. A small cell lung carcinoma was discovered 40 months after renal transplantation, with a fatal outcome 6 months later. Four clinically occult apudomas were found at autopsy, including one gastric and one bronchial carcinoid tumor, one multicentric pancreatic islet cell neoplasm, and one case of multiple ileal carcinoids. With the exception of the small cell lung cancer, none of the apudomas was clinically significant, and none was associated with carcinoid or other paraneoplastic syndrome. These cases illustrate the difficulty of diagnosis of apudomas in patients with renal failure and the usually benign nature of these tumors despite the administration of potent immunosuppressive agents.

All patients who had three or more major joints (hips or knees) replaced were identified from operation records at one hospital and reviewed to assess outcome. Forty-three were found to suffer from rheumatoid arthritis, four from osteoarthritis and three from psoriatic arthritis. Eight patients had died an average of 2.6 years (range 1-7 years) after their last operation and this was higher than expected, even for RA. Average follow-up in the 36 surviving RA sufferers was 1.8 years, with a minimum of 6 months since last operation. Range of joint movement, pain relief, satisfaction, mobility, disability and social outcomes were assessed and are reported. Patients were satisfied with outcome because of pain relief and functional improvement. No patient required permanent in-patient care, although they still represented a very disabled group with mean HAQ score of 2.75.