The rapid assembly of an elliptical galaxy of 400 billion solar masses at a redshift of 2.3.

Stellar archaeology shows that massive elliptical galaxies formed rapidly about ten billion years ago with star-formation rates of above several hundred solar masses per year. Their progenitors are probably the submillimetre bright galaxies at redshifts z greater than 2. Although the mean molecular gas mass (5 × 10(10) solar masses) of the submillimetre bright galaxies can explain the formation of typical elliptical galaxies, it is inadequate to form elliptical galaxies that already have stellar masses above 2 × 10(11) solar masses at z ≈ 2. Here we report multi-wavelength high-resolution observations of a rare merger of two massive submillimetre bright galaxies at z = 2.3. The system is seen to be forming stars at a rate of 2,000 solar masses per year. The star-formation efficiency is an order of magnitude greater than that of normal galaxies, so the gas reservoir will be exhausted and star formation will be quenched in only around 200 million years. At a projected separation of 19 kiloparsecs, the two massive starbursts are about to merge and form a passive elliptical galaxy with a stellar mass of about 4 × 10(11) solar masses. We conclude that gas-rich major galaxy mergers with intense star formation can form the most massive elliptical galaxies by z ≈ 1.5.

Intense star formation within resolved compact regions in a galaxy at z = 2.3.

Massive galaxies in the early Universe have been shown to be forming stars at surprisingly high rates. Prominent examples are dust-obscured galaxies which are luminous when observed at sub-millimetre wavelengths and which may be forming stars at a rate of 1,000 solar masses (M(middle dot in circle)) per year. These intense bursts of star formation are believed to be driven by mergers between gas-rich galaxies. Probing the properties of individual star-forming regions within these galaxies, however, is beyond the spatial resolution and sensitivity of even the largest telescopes at present. Here we report observations of the sub-millimetre galaxy SMMJ2135-0102 at redshift z = 2.3259, which has been gravitationally magnified by a factor of 32 by a massive foreground galaxy cluster lens. This magnification, when combined with high-resolution sub-millimetre imaging, resolves the star-forming regions at a linear scale of only 100 parsecs. We find that the luminosity densities of these star-forming regions are comparable to the dense cores of giant molecular clouds in the local Universe, but they are about a hundred times larger and 10(7) times more luminous. Although vigorously star-forming, the underlying physics of the star-formation processes at z approximately 2 appears to be similar to that seen in local galaxies, although the energetics are unlike anything found in the present-day Universe.

On the redshift distribution and physical properties of ACT-selected DSFGs.

We present multi-wavelength detections of nine candidate gravitationally-lensed dusty star-forming galaxies (DSFGs) selected at 218GHz (1.4mm) from the ACT equatorial survey. Among the brightest ACT sources, these represent the subset of the total ACT sample lying in Herschel SPIRE fields, and all nine of the 218GHz detections were found to have bright Herschel counterparts. By fitting their spectral energy distributions (SEDs) with a modified blackbody model with power-law temperature distribution, we find the sample has a median redshift of z = 4.1 - 1.0 + 1.1 (68 per cent confidence interval), as expected for 218GHz selection, and an apparent total infrared luminosity of log 10 ( µ L IR / L ⊙ ) = 13.86 - 0.30 + 0.33 , which suggests that they are either strongly lensed sources or unresolved collections of unlensed DSFGs. The effective apparent diameter of the sample is µ d = 4.2 - 1.0 + 1.7 kpc , further evidence of strong lensing or multiplicity, since the typical diameter of dusty star-forming galaxies is 1.0-2.5 kpc. We emphasize that the effective apparent diameter derives from SED modelling without the assumption of optically thin dust (as opposed to image morphology). We find that the sources have substantial optical depth. ( τ = 4.2 - 1.9 + 3.7 ) to dust around the peak in the modified blackbody spectrum (λ obs ⩽ 500µm), a result that is robust to model choice.

Arthroplasty with a composite of an allograft and a prosthesis for knees with severe deficiency of bone.

We reviewed the clinical and radiographic results of fourteen patients who had a severe deficiency of bone and were managed with a massive allograft in conjunction with a standard total knee prosthesis between 1987 and 1990. The etiology of the bone loss included the failure of a previous total knee prosthesis, a supracondylar fracture of the femur or a fracture of the proximal part of the tibia, and débridement during the first stage of a reconstruction for the treatment of an infection. Thirteen patients had satisfactory clinical and radiographic results after the index procedure. The knee score of The Hospital for Special Surgery improved from an average of 24 points (range, 0 to 54 points) preoperatively to 82 points (range, 37 to 98 points) at the time of the most recent follow-up examination. The average duration of follow-up was forty-three months (range, twenty-nine to sixty-three months). The radiographic and functional results compare favorably with those that have been reported in most studies of otherwise comparable patients who had less deficiency of bone. While considerable risks are associated with the use of allograft bone and the true longevity of reconstructions with such bone is not yet known, the initial and short-term follow-up results support the use of allograft for the restoration of a functional knee joint in a patient who has a severe deficiency of bone.

Allograft prosthetic composite reconstruction for limb salvage and severe deficiency of bone at the knee or hip.

We reviewed the clinical, radiographic, and where applicable, oncologic results of 112 consecutive allograft prosthetic composite reconstructions performed at Rush Presbyterian St Luke's Medical Center. The source of the bone defects included resection of a tumor, failure of a prior arthroplasty, and periprosthetic fracture. The patients having reconstruction after tumor resection achieved an average Enneking functional score of 28.3. Satisfactory clinical and radiographic results were obtained in 70% to 93%, depending on the group. Based on our experience, we have established a set of principles that should maximize functional results and minimize problems with allograft prosthetic composite arthroplasty.

Note: cryogenic microstripline-on-Kapton microwave interconnects.

Simple broadband microwave interconnects are needed for increasing the size of focal plane heterodyne radiometer arrays. We have measured loss and crosstalk for arrays of microstrip transmission lines in flex circuit technology at 297 and 77 K, finding good performance to at least 20 GHz. The dielectric constant of Kapton substrates changes very little from 297 to 77 K, and the electrical loss drops. The small cross-sectional area of metal in a printed circuit structure yields overall thermal conductivities similar to stainless steel coaxial cable. Operationally, the main performance tradeoffs are between crosstalk and thermal conductivity. We tested a patterned ground plane to reduce heat flux.

Chronic active hepatitis and ulcerative colitis associated with eosinophilia, nonthrombocytopenic hypergammaglobulinemic purpura and serologic abnormalities.

A patient with chronic active hepatitis (CAH) and ulcerative colitis (UC) associated with eosinophilia, nonthrombocytopenic hypergammaglobulinemic purpura and serologic abnormalities is presented. Abnormal liver function, gastrointestinal and systemic symptoms as well as the associated epiphenomena responded dramatically to oral corticosteroid therapy. The remission was maintained during an eight month follow-up period with low dose prednisone therapy.

The radiology corner: Longitudinal fistulous tract of the colon and a perianal fistula in diverticulitis.

Diverticular disease may mimic many of the symptoms and signs of Crohn's disease. The presence, however, of perirectal involvement and a longitudinal fistula greater than 10 cm. in the wall of the colon are two unusual features of diverticular disease. Discussed herein is a patient who presented with both of these complications.

Acute suppurative cholangitis secondary to calcific pancreatitis.

In the absence of calculi or carcinoma, the occurrence of acute suppurative cholangitis secondary to calcific pancreatitis is extremely rare. This report describes the successful management of acute suppurative cholangitis by surgical decompression and use of a new aminoglycoside, amikacin.

Massive heterotopic ossification after biceps tendon rupture and tenodesis.

Few complications from tenodesis of the long head of the biceps brachii have been described despite the wide variety of techniques. In a 53-year-old man, rupture of this tendon was treated by tenodesis and was complicated by heterotopic ossification that severely limited the function of the shoulder joints. Nonsurgical conservative treatment of biceps tendon ruptures may avoid the possibility of this complication.