Seismic imaging of rapid onset of stratified turbulence in the South Atlantic Ocean

AbstractBroadband measurements of the internal wavefield will help to unlock an understanding of the energy cascade within the oceanic realm. However, there are challenges in acquiring observations with sufficient spatial resolution, especially in horizontal dimensions. Seismic reflection profiling can achieve a horizontal and vertical resolution of order meters. It is suitable for imaging thermohaline fine structure on scales that range from tens of meters to hundreds of kilometers. This range straddles the transition from internal wave to turbulent regimes. Here, the authors analyze an 80-km-long seismic image from the Falkland Plateau and calculate vertical displacement spectra of tracked reflections. First, they show that these spectra are consistent with the Garrett–Munk model at small horizontal wavenumbers (i.e., kx ≲ 3 × 10−3 cpm). There is a transition to stratified turbulence at larger wavenumbers (i.e., kx ≳ 2 × 10−1 cpm). This transition occurs at length scales that are significantly larger than the Ozmidov length scale above which stratification is expected to modify isotropic Kolmogorov turbulence. Second, the authors observe a rapid onset of this stratified turbulence over a narrow range of length scales. This onset is consistent with a characteristic energy injection scale of stratified turbulence with a forward cascade toward smaller scales through isotropic turbulence below the Ozmidov length scale culminating in microscale dissipation. Finally, they estimate the spatial pattern of diapycnal diffusivity and show that the existence of an injection scale can increase these estimates by a factor of 2.M.F. is supported by the Department of Earth Sciences. Research activity of C.P.C. is supported by EPSRC Programme Grant EP/K034529/1 (“Mathematical Underpinnings of Stratified Turbulence”). We thank C. Bond, A. Dickinson, K. Gunn, S. Holbrook, J. Klymak, J. Moum and S. Thorpe for their help. We are very grateful to J. Klymak for generously making available his MATLAB toolbox for calculating Garrett-Munk spectra. Department of Earth Sciences contribution number esc.XXXX.This is the author accepted manuscript. The final version is available from the American Meteorological Society via http://dx.doi.org/10.1175/JPO-D-15-0140.

Three-dimensional arrangement of elastic fibers in the human corneal stroma

This is the final version of the article. Available from the publisher via the DOI in this record.The cornea is the main refracting lens in the eye. As part of the outer tunic it has to be resilient, a property conferred by the organisation of the constituent collagen. It also has to be sufficiently elastic to regain its exact shape when deformed, in order not to distort the retinal image. The basis of this elasticity is not fully understood. The purpose of this study was to characterise in three dimensions the arrangement and distribution of elastic fibers in the human corneal stroma, using serial block face scanning electron microscopy. We have demonstrated that there exists a complex network of elastic fibers that appear to originate in the sclera or limbus. These appear as elastic sheets in the limbus and peripheral cornea immediately above the trabecular meshwork which itself appears to extend above Descemet's membrane in the peripheral stroma. From these sheets, elastic fibers extend into the cornea; moving centrally they bifurcate and trifurcate into narrower fibers and are concentrated in the posterior stroma immediately above Descemet's membrane. We contend that elastic sheets will play an important role in the biomechanical deformation and recovery of the peripheral cornea. The network may also have practical implications for understanding the structural basis behind a number of corneal surgeries.We would like to thank Dr Anthony Hayes and Mr Derek Scarborough for help with the histology presented in this study and Dr Sally Hayes for useful discussions concerning data interpretation. This work was funded by a Programme Grant (503626) from the Medical Research Council (to KMM) and an MRC studentship (to TW). We thank the CTC Eye Bank at Bristol, UK and the HDBR at Newcastle, UK, for supply of human corneas. The authors have no conflicts of interest to declare

Searching (the) FIRST radio arcs near ACO clusters

Gravitational lensing (GL) of distant radio sources by galaxy clusters should produce radio arc(let)s. We extracted radio sources from the FIRST survey near Abell cluster cores and found their radio position angles to be uniformly distributed with respect to the cluster centres. This result holds even when we restrict the sample to the richest or most centrally condensed clusters, and to sources with high S/N and large axial ratio. Our failure to detect GL with statistical methods may be due to poor cluster centre positions. We did not find convincing candidates for arcs either. Our result agrees with theoretical estimates predicting that surveys much deeper than FIRST are required to detect the effect. This is in apparent conflict with the detection of such an effect claimed by Bagchi & Kapahi (1995).Comment: 6 pages; 8 figures and 1 style file are included; to appear in Proc. "Observational Cosmology with the New Radio Surveys", eds. M. Bremer, N. Jackson & I. Perez-Fournon, Kluwer Acad. Pres

Antifungal Susceptibility Profiles of 1698 Yeast Reference Strains Revealing Potential Emerging Human Pathogens

New molecular identification techniques and the increased number of patients with various immune defects or underlying conditions lead to the emergence and/or the description of novel species of human and animal fungal opportunistic pathogens. Antifungal susceptibility provides important information for ecological, epidemiological and therapeutic issues. The aim of this study was to assess the potential risk of the various species based on their antifungal drug resistance, keeping in mind the methodological limitations. Antifungal susceptibility profiles to the five classes of antifungal drugs (polyens, azoles, echinocandins, allylamines and antimetabolites) were determined for 1698 yeast reference strains belonging to 992 species (634 Ascomycetes and 358 Basidiomycetes). Interestingly, geometric mean minimum inhibitory concentrations (MICs) of all antifungal drugs tested were significantly higher for Basidiomycetes compared to Ascomycetes (p<0.001). Twenty four strains belonging to 23 species of which 19 were Basidiomycetes seem to be intrinsically “resistant” to all drugs. Comparison of the antifungal susceptibility profiles of the 4240 clinical isolates and the 315 reference strains belonging to 53 shared species showed similar results. Even in the absence of demonstrated in vitro/in vivo correlation, knowing the in vitro susceptibility to systemic antifungal agents and the putative intrinsic resistance of yeast species present in the environment is important because they could become opportunistic pathogens

New evidence on Allyn Young's style and influence as a teacher

This paper publishes the hitherto unpublished correspondence between Allyn Abbott Young's biographer Charles Blitch and 17 of Young's former students or associates. Together with related biographical and archival material, the paper shows the way in which this adds to our knowledge of Young's considerable influence as a teacher upon some of the twentieth century's greatest economists. The correspondents are as follows: James W Angell, Colin Clark, Arthur H Cole, Lauchlin Currie, Melvin G de Chazeau, Eleanor Lansing Dulles, Howard S Ellis, Frank W Fetter, Earl J Hamilton, Seymour S Harris, Richard S Howey, Nicholas Kaldor, Melvin M Knight, Bertil Ohlin, Geoffrey Shepherd, Overton H Taylor, and Gilbert Walker

A family case of fertile human 45,X,psu dic(15;Y) males

We report on a familial case including four male probands from three generations with a 45,X,psu dic(15;Y)(p11.2;q12) karyotype. 45,X is usually associated with a female phenotype and only rarely with maleness, due to translocation of small Y chromosomal fragments to autosomes. These male patients are commonly infertile because of missing azoospermia factor regions from the Y long arm. In our familial case we found a pseudodicentric translocation chromosome, that contains almost the entire chromosomes 15 and Y. The translocation took place in an unknown male ancestor of our probands and has no apparent effect on fertility and phenotype of the carrier. FISH analysis demonstrated the deletion of the pseudoautosomal region 2 (PAR2) from the Y chromosome and the loss of the nucleolus organizing region (NOR) from chromosome 15. The formation of the psu dic(15;Y) chromosome is a reciprocal event to the formation of the satellited Y chromosome (Yqs). Statistically, the formation of 45,X,psu dic(15;Y) (p11.2;q12) is as likely as the formation of Yqs. Nevertheless, it has not been described yet. This can be explained by the dicentricity of this translocation chromosome that usually leads to mitotic instability and meiotic imbalances. A second event, a stable inactivation of one of the two centromeres is obligatory to enable the transmission of the translocation chromosome and thus a stably reduced chromosome number from father to every son in this family

Ethanol reversal of tolerance to the respiratory depressant effects of morphine

Opioids are the most common drugs associated with unintentional drug overdose. Death results from respiratory depression. Prolonged use of opioids results in the development of tolerance but the degree of tolerance is thought to vary between different effects of the drugs. Many opioid addicts regularly consume alcohol (ethanol), and post-mortem analyses of opioid overdose deaths have revealed an inverse correlation between blood morphine and ethanol levels. In the present study, we determined whether ethanol reduced tolerance to the respiratory depressant effects of opioids. Mice were treated with opioids (morphine, methadone, or buprenorphine) for up to 6 days. Respiration was measured in freely moving animals breathing 5% CO(2) in air in plethysmograph chambers. Antinociception (analgesia) was measured as the latency to remove the tail from a thermal stimulus. Opioid tolerance was assessed by measuring the response to a challenge dose of morphine (10 mg/kg i.p.). Tolerance developed to the respiratory depressant effect of morphine but at a slower rate than tolerance to its antinociceptive effect. A low dose of ethanol (0.3 mg/kg) alone did not depress respiration but in prolonged morphine-treated animals respiratory depression was observed when ethanol was co-administered with the morphine challenge. Ethanol did not alter the brain levels of morphine. In contrast, in methadone- or buprenorphine-treated animals no respiratory depression was observed when ethanol was co-administered along with the morphine challenge. As heroin is converted to morphine in man, selective reversal of morphine tolerance by ethanol may be a contributory factor in heroin overdose deaths

The mass distribution of the unusual merging cluster Abell 2146 from strong lensing

Abell 2146 consists of two galaxy clusters that have recently collided close to the plane of the sky, and it is unique in showing two large shocks on $\textit{Chandra X-ray Observatory}$ images. With an early stage merger, shortly after first core passage, one would expect the cluster galaxies and the dark matter to be leading the X-ray emitting plasma. In this regard, the cluster Abell 2146-A is very unusual in that the X-ray cool core appears to lead, rather than lag, the brightest cluster galaxy (BCG) in their trajectories. Here we present a strong-lensing analysis of multiple-image systems identified on $\textit{Hubble Space Telescope}$ images. In particular, we focus on the distribution of mass in Abell 2146-A in order to determine the centroid of the dark matter halo. We use object colours and morphologies to identify multiple-image systems; very conservatively, four of these systems are used as constraints on a lens mass model. We find that the centroid of the dark matter halo, constrained using the strongly lensed features, is coincident with the BCG, with an offset of ≈2 kpc between the centres of the dark matter halo and the BCG. Thus from the strong-lensing model, the X-ray cool core also leads the centroid of the dark matter in Abell 2146-A, with an offset of ≈30 kpc.JEC acknowledges support from The University of Texas at Dallas, and NASA through a Fellowship of the Texas Space Grant Consortium. Based on observations made with the NASA/ESA HST, obtained through programme 12871 through the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Additional funding supporting JEC, LJK, and DIC came from a grant from the Space Telescope Science Institute under the same programme 12871. Additional funding supporting JEC and LJK came from a grant from the National Science Foundation, number 1517954. This work was supported in part by World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan, and JSPS KAKENHI Grant Number 26800093 and 15H05892