The suppression of star formation by powerful active galactic nuclei.

The old, red stars that constitute the bulges of galaxies, and the massive black holes at their centres, are the relics of a period in cosmic history when galaxies formed stars at remarkable rates and active galactic nuclei (AGN) shone brightly as a result of accretion onto black holes. It is widely suspected, but unproved, that the tight correlation between the mass of the black hole and the mass of the stellar bulge results from the AGN quenching the surrounding star formation as it approaches its peak luminosity. X-rays trace emission from AGN unambiguously, whereas powerful star-forming galaxies are usually dust-obscured and are brightest at infrared and submillimetre wavelengths. Here we report submillimetre and X-ray observations that show that rapid star formation was common in the host galaxies of AGN when the Universe was 2-6 billion years old, but that the most vigorous star formation is not observed around black holes above an X-ray luminosity of 10(44) ergs per second. This suppression of star formation in the host galaxy of a powerful AGN is a key prediction of models in which the AGN drives an outflow, expelling the interstellar medium of its host and transforming the galaxy's properties in a brief period of cosmic time.

Submillimetre galaxies reside in dark matter haloes with masses greater than 3 × 10(11) solar masses.

The extragalactic background light at far-infrared wavelengths comes from optically faint, dusty, star-forming galaxies in the Universe with star formation rates of a few hundred solar masses per year. These faint, submillimetre galaxies are challenging to study individually because of the relatively poor spatial resolution of far-infrared telescopes. Instead, their average properties can be studied using statistics such as the angular power spectrum of the background intensity variations. A previous attempt at measuring this power spectrum resulted in the suggestion that the clustering amplitude is below the level computed with a simple ansatz based on a halo model. Here we report excess clustering over the linear prediction at arcminute angular scales in the power spectrum of brightness fluctuations at 250, 350 and 500 µm. From this excess, we find that submillimetre galaxies are located in dark matter haloes with a minimum mass, M(min), such that log(10)[M(min)/M(⊙)] = 11.5(+0.7)(-0.2) at 350 µm, where M(⊙) is the solar mass. This minimum dark matter halo mass corresponds to the most efficient mass scale for star formation in the Universe, and is lower than that predicted by semi-analytical models for galaxy formation.

The detection of a population of submillimeter-bright, strongly lensed galaxies.

Gravitational lensing is a powerful astrophysical and cosmological probe and is particularly valuable at submillimeter wavelengths for the study of the statistical and individual properties of dusty star-forming galaxies. However, the identification of gravitational lenses is often time-intensive, involving the sifting of large volumes of imaging or spectroscopic data to find few candidates. We used early data from the Herschel Astrophysical Terahertz Large Area Survey to demonstrate that wide-area submillimeter surveys can simply and easily detect strong gravitational lensing events, with close to 100% efficiency.

[Diagnostic value of the assay of beta 2 microglobulin during the monitoring of surgically-treated colorectal cancers. Comparison with carcinoembryonic antigen]. / Valeur diagnostique du dosage de la beta 2-microglobuline au cours de la surveillance des cancers colo-rectaux opérés. Comparaison avec l'antigéne carcino-embryonnaire.

This work presents an evaluation of the diagnostic value of seric beta 2-microglobulin in the follow-up of operated colorectal cancers. Ninety-one patients were operated on with a curative intent between 1976 and 1979. These patients were followed for at least 2 years and divided in 2 groups: a) group NR: 48 patients apparently free of loco-regional recurrence and of distant metastases, b) group R: 43 patients presenting a cancerous relapse. High levels of beta 2-microglobulin were found in 21 patients of group NR (specificity: 56 p. 100) and in 25 patients of group R (sensitivity: 58 p. 100). In the same population, the specificity and the sensitivity of carcinoembryonic antigen (CEA) for the diagnosis of a relapse were 92 p. 100 and 88 p. 100 respectively. No significant statistical correlation was observed between the levels of beta 2-microglobulin and CEA. The sensitivity of the association beta 2-microglobulin + CEA was not superior to the dosage of CEA alone despite its reduced specificity (54 p. 100). These results indicate that the diagnostic value of the dosage of beta 2-microglobulin is inferior to that of CEA and is without interest for the detection of tumoral recurrence in the postoperative follow-up of colorectal cancers.

[Colonic occlusions. Retrospective cooperative study of 497 cases]. / Les occlusions coliques. Etude rétrospective coopérative de 497 cas.

A retrospective multicenter study involving 12 digestive surgery centers was conducted on 497 cases of colon obstruction. The most frequent cause of colon obstruction was colo-rectal cancer (71 p. cent of cases), but many other etiologies were involved, including 61 cases of torsion and 37 patients with occlusive sigmoiditis. Differential clinical and radiological features in each etiological group are discussed, the results of therapy undertaken analyzed, and a reasonable line of conduct proposed, adapted to each situation, with the objective of attempting to reduce mortality which still affects 25 p. cent of cases operated upon.

[Dermatomyositis and colonic cancer. Review of the literature apropos of a case]. / Dermatomyosite et cancer colique. Revue de la littérature à propos d'un cas.

The authors report the case of a 56 year-old woman presenting with dermatomyositis revealing a cancer of the colon at the ganglial dissemination stage. Exeresis led to the regression of the dermatomyositis and allowed an attenuation of the steroid therapy. The muscular and cutaneous signs reappeared within six months, evidencing a metastatic hepatic dissemination. Death came within six months of the appearance of the dermatomyositis. The authors review the literature concerning dermatomyositis associated with cancers of the digestive tract in general, and of the colon in particular. This association is found in about 6 to 35% of cases of dermatomyositis, which is the most common paraneoplastic skin associated with cancers of the colon.

[Parathyroid risk in thyroid surgery. Reality and prevention. 502 bilateral thyroidectomies]. / Le risque parathyroïdien en chirurgie thyroïdienne. Sa réalité et sa prévention. 502 exérèses bilatérales.

Prospective study of parathyroid risk in a bulk of 502 consecutive bilateral thyroidectomies. Early post-operative hypocalcemia has been documented in 8,8% of the patients, but persisted in only 1,6% one year later. Late parathyroid risk of total thyroidectomy is 3,3% but increases twofold if neck dissection is simultaneously performed. Methods of this study probably misdiagnose a number of mild hypoparathyroidism. Lack of early hyperphosphoremia seems to be an optimizing criteria for aftermath. In Grave's disease, early post-operative hypocalcemia is more common (6,9%) but often subsides (definitive risk: 0,4%). This acceptable morbidity is compared to the data of literature. To prevent post-operative hypoparathyroidism a painstaking dissection of parathyroid blood supply seems more promising and effective than routine autotransplantation of the glands.