BLAST: Correlations in the Cosmic Far-Infrared Background at 250, 350, and 500 microns Reveal Clustering of Star-Forming Galaxies

We detect correlations in the cosmic far-infrared background due to the clustering of star-forming galaxies in observations made with the Balloon-borne Large Aperture Submillimeter Telescope, BLAST, at 250, 350, and 500 microns. We perform jackknife and other tests to confirm the reality of the signal. The measured correlations are well fit by a power law over scales of 5-25 arcminutes, with Delta I/I = 15.1 +/- 1.7%. We adopt a specific model for submillimeter sources in which the contribution to clustering comes from sources in the redshift ranges 1.3 <= z <= 2.2, 1.5 <= z <= 2.7, and 1.7 <= z <= 3.2, at 250, 350, and 500 microns, respectively. With these distributions, our measurement of the power spectrum, P(k_theta), corresponds to linear bias parameters, b = 3.8 +/- 0.6, 3.9 +/- 0.6 and 4.4 +/- 0.7, respectively. We further interpret the results in terms of the halo model, and find that at the smaller scales, the simplest halo model fails to fit our results. One way to improve the fit is to increase the radius at which dark matter halos are artificially truncated in the model, which is equivalent to having some star-forming galaxies at z >= 1 located in the outskirts of groups and clusters. In the context of this model we find a minimum halo mass required to host a galaxy is log (M_min / M_sun) = 11.5 (+0.4/-0.1), and we derive effective biases $b_eff = 2.2 +/- 0.2, 2.4 +/- 0.2, and 2.6 +/- 0.2, and effective masses log (M_eff / M_sun) = 12.9 +/- 0.3, 12.8 +/- 0.2, and 12.7 +/- 0.2, at 250, 350, and 500 microns, corresponding to spatial correlation lengths of r_0 = 4.9, 5.0, and 5.2 +/- 0.7 h^-1 Mpc, respectively. Finally, we discuss implications for clustering measurement strategies with Herschel and Planck.Comment: Accepted for publication in the Astrophysical Journal. Maps and other results available at http://blastexperiment.info

DYNAMO - I. A sample of H alpha-luminous galaxies with resolved kinematics

DYNAMO is a multiwavelength, spatially resolved survey of local (z ∼ 0.1) star-forming galaxies designed to study evolution through comparison with samples at z _ 2. Half of the sample has integrated Hα luminosities of >1042 erg s−1, the typical lower limit for resolved spectroscopy at z _ 2. The sample covers a range in stellar mass (109–1011M_) and star formation rate (0.2–100M_ yr−1). In this first paper of a series, we present integral-field spectroscopy of Hα emission for the sample of 67 galaxies. We infer gas fractions in our sample as high as _0.8, higher than typical for local galaxies. Gas fraction correlates with stellarmass in galaxies with star formation rates below 10M_ yr−1, as found by COLDGASS, but galaxies with higher star formation rates have higher than expected gas fractions. There is only a weak correlation, if any, between gas fraction and gas velocity dispersion. Galaxies in the sample visually classified as disc-like are offset from the local stellar mass Tully–Fisher relation to higher circular velocities, but this offset vanishes when both gas and stars are included in the baryonic Tully–Fisher relation. The mean gas velocity dispersion of the sample is_50 km s−1, and V/σ ranges from 2 to 10 for most of the discs, similar to ‘turbulent’ galaxies at high redshift. Half of our sample show disc-like rotation, while ∼20 per cent show no signs of rotation. The division between rotating and non-rotating is approximately equal for the sub-samples with either star formation rates >10M_ yr−1, or specific star formation rates typical of the star formation ‘main sequence’ at z _ 2. Across our whole sample, we find good correlation between the dominance of ‘turbulence’ in galaxy discs (as expressed by V/σ ) and gas fraction as has been predicted for marginally stable Toomre discs. Comparing our sample with many others at low- and high-redshift reveals a correlation between gas velocity dispersion and star formation rate. These findings suggest the DYNAMO discs are excellent candidates for local galaxies similar to turbulent z _ 2 disc galaxies

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Infections in Periarticular Fractures of the Lower Extremity Treated with Tensioned Wire Hybrid Fixators

OBJECTIVES:To observe the incidence and clinical presentation of infection in periarticular fractures of the tibia and femur treated with tensioned wire external fixators. DESIGN:Prospective cohort study. SETTING:Level One Trauma Center in urban community. Single surgeon. PATIENTS:One hundred thirty-five patients with 145 fracturesseventy tibial plateau, fifty-six pilon, and nineteen distal femur. Five-year treatment period, 1991 to 1995. MAIN OUTCOME MEASUREMENTS:The incidence of infection was evaluated. RESULTS:Nineteen of 145 fractures (13 percent) were complicated by infection. Infections presented as pin tract inflammation requiring intravenous antibiotics (seven), deep infection requiring debridement and removal (five), septic arthritis (three), deep fracture infection (three), and necrotizing fasciitis (one). CONCLUSIONS:Infection is a common complication of juxtaarticular fractures treated with tensioned wire fixators. Excellent pin care is required. Aggressive management of infections with intravenous antibiotics and debridement will resolve infections occurring in patients treated with tensioned wire fixators. Septic arthritis is associated with wires placed less than one centimeter from the subchondral bone. Deep infection is associated with insidious swelling and excessive proliferative callus. Wire infections increase with prolonged frame time

Acute Psoas Abscess in a Newborn Infant

SUMMARYA 1-month-old neonate was seen for an acute toxic illness, suggestive of septicemia. No obvious focus of infection was present. During attempted femoral venipuncture, purulent material, thought to originate from the right hip joint, was encountered. Because of this aspirate, as well as suggestive local signs, septic arthritis of the right hip was diagnosed. Arthrotomy failed to confirm the diagnosis, and on further surgical exploration a purulent psoas abscess was discovered. The patient made an uneventful recovery, and at follow-up 48 months later was asymptomatic with a normal clinical examination. This case illustrates the difficulty of differentiating acute psoas abscess from septic arthritis of the hip in the neonate

Part II: The mechanics of fracture fixation

A wide variety of options are available for fixation of fractures. Mechanical stability is generally not necessary for fracture healing, but is important for maintaining alignment to prevent malunion. The degree of angulation, rotation and shortening which can be tolerated and still be compatible with good function is dependent upon the particular type of fracture, its location and the expected performance of the patient. In general, the stiffer the fixation is, the less the fracture site will move, the less callus will form and the less is the stress on the healing tissues. The less stiff (or more compliant) the fixation, the more abundant the peripheral callus and the more stress on the tissues as they form to optimize tissue alignment, strength and stiffness. External fixation provides the best control of structural stiffness of fixation and provides the option of changing the stiffness during the treatment. Of the internal fixation methods, intramedullary fixation devices are the least biologically invasive option and least mechanically destructive. Plate fixation provides the most stable, rigid fixation but the greatest alteration of the natural healing processes. Functional cost or fracture brace management provides the least stable, most compliant fixation and the least interference with the natural healing processes. Each has its place in the armamentarium of the orthopaedic trauma surgeon