513 research outputs found

    The geology of zinc in coals of the Illinois Basin

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    Final report to the U.S. Geological Survey, Branch of Eastern Mineral Resources, U.S. Department of Interior. June 1975 to September 1977.U.S. Department of Interior Grant 14-08-0001-G-249Ope

    Quark Effects in the Gluon Condensate Contribution to the Scalar Glueball Correlation Function

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    One-loop quark contributions to the dimension-four gluon condensate term in the operator product expansion (OPE) of the scalar glueball correlation function are calculated in the MS-bar scheme in the chiral limit of nfn_f quark flavours. The presence of quark effects is shown not to alter the cancellation of infrared (IR) singularities in the gluon condensate OPE coefficients. The dimension-four gluonic condensate term represents the leading power corrections to the scalar glueball correlator and, therein, the one-loop logarithmic contributions provide the most important condensate contribution to those QCD sum-rules independent of the low-energy theorem (the subtracted sum-rules).Comment: latex2e, 6 pages, 7 figures embedded in latex fil

    Intra and inter-observer agreement on polyp detection in colon capsule endoscopy evaluations

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    Background: Colon capsule endoscopy is a promising technique for evaluation of the colon, but its reproducibility is still unknown. Objective: This study assesses intra and inter-observer agreement in evaluations of colon capsule endoscopy videos. Methods: Forty-two complete colon capsule endoscopy investigations were analysed by three experts and two beginners. Intra-observer agreement was assessed in paired readings of two experts and two beginners. Agreement was determined by the intraclass correlation coefficient: poor (&lt;0.5), moderate (0.5–0.75), good (0.75–0.9) and excellent (&gt;0.9). Results: Agreement on ‘indication for a following colonoscopy’ based on the number and size of detected polyps and bowel cleansing quality was poor among all observers. Agreement among experts on the detection of large polyps and number of polyps was moderate, but agreement on bowel cleansing quality was poor. Beginners were in moderate agreement with the experts on polyp detection. Intra-observer agreement in experts was moderate to excellent for the detection of large polyps (≥10 mm), excellent for the number of polyps, and poor to moderate for bowel cleansing quality. Intra-observer agreement in beginners was poor to moderate for all variables. Conclusions: This study shows a poor agreement on ‘indication for a following colonoscopy’, but a high intra and inter-observer agreement for polyp detection among experts, as well as a moderate agreement between beginners and experts.</p

    Protection of cells from salinity stress by extracellular polymeric substances in diatom biofilms.

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    Diatom biofilms are abundant in the marine environment. It is assumed (but untested) that extracellular polymeric substances (EPS), produced by diatoms, enable cells to cope with fluctuating salinity. To determine the protective role of EPS, Cylindrotheca closterium was grown in xanthan gum at salinities of 35, 50, 70 and 90 ppt. A xanthan matrix significantly increased cell viability (determined by SYTOX-Green), growth rate and population density by up to 300, 2,300 and 200%, respectively. Diatoms grown in 0.75% w/v xanthan, subjected to acute salinity shock treatments (at salinities 17.5, 50, 70 and 90 ppt) maintained photosynthetic capacity, Fq'/Fm', within 4% of pre-shock values, whereas Fq'/Fm' in cells grown without xanthan declined by up to 64% with hypersaline shock. Biofilms that developed in xanthan at standard salinity helped cells to maintain function during salinity shock. These results provide evidence of the benefits of living in an EPS matrix for biofilm diatoms

    The SF3B1 inhibitor spliceostatin A (SSA) elicits apoptosis in chronic lymphocytic leukemia cells through downregulation of Mcl-1

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    The pro-survival Bcl-2 family member Mcl-1 is expressed in chronic lymphocytic leukemia (CLL), with high expression correlated with progressive disease. The spliceosome inhibitor spliceostatin A (SSA), is known to regulate Mcl-1 and so here we assessed the ability of SSA to elicit apoptosis in CLL. SSA induced apoptosis of CLL cells at low nanomolar concentrations in a dose- and time-dependent manner, but independently of SF3B1 mutational status, IGHV status and CD38 or ZAP70 expression. However, normal B and T cells were less sensitive than CLL cells (P=0.006 and P&lt;0.001, respectively). SSA altered the splicing of anti-apoptotic MCL-1L to MCL-1s in CLL cells coincident with induction of apoptosis. Overexpression studies in Ramos cells suggested Mcl-1 was important for SSA-induced killing since its expression inversely correlated with apoptosis (P=0.001). IL4 and CD40L, present in patient lymph nodes, are known to protect tumor cells from apoptosis and significantly inhibited SSA, ABT-263 and ABT-199 induced killing following administration to CLL cells (P=0.008). However, by combining SSA with the Bcl-2/Bcl-xL antagonists ABT-263 or ABT-199, we were able to overcome this pro-survival effect. We conclude that SSA combined with Bcl-2/Bcl-xL antagonists may have therapeutic utility for CL

    Colorectal cancer screening in the UK:A public health intervention of unrealised potential

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    The United Kingdom was one of the first countries in the world to have a fully rolled out colorectal cancer screening programme and, although the four constituent countries have taken somewhat different approaches, they all commenced with guaiac faecal occult blood testing and have all now transitioned to faecal immunochemical testing. In this Commentary, we trace the development of the Scottish Bowel Screening Programme, with reference to the other UK programmes, reflect on its successes and shortcomings, and make suggestions for the future.</p

    Thin-Film Metamaterials called Sculptured Thin Films

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    Morphology and performance are conjointed attributes of metamaterials, of which sculptured thin films (STFs) are examples. STFs are assemblies of nanowires that can be fabricated from many different materials, typically via physical vapor deposition onto rotating substrates. The curvilinear--nanowire morphology of STFs is determined by the substrate motions during fabrication. The optical properties, especially, can be tailored by varying the morphology of STFs. In many cases prototype devices have been fabricated for various optical, thermal, chemical, and biological applications.Comment: to be published in Proc. ICTP School on Metamaterials (Augsut 2009, Sibiu, Romania

    Boson gas in a periodic array of tubes

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    We report the thermodynamic properties of an ideal boson gas confined in an infinite periodic array of channels modeled by two, mutually perpendicular, Kronig-Penney delta-potentials. The particle's motion is hindered in the x-y directions, allowing tunneling of particles through the walls, while no confinement along the z direction is considered. It is shown that there exists a finite Bose- Einstein condensation (BEC) critical temperature Tc that decreases monotonically from the 3D ideal boson gas (IBG) value T0T_{0} as the strength of confinement P0P_{0} is increased while keeping the channel's cross section, axaya_{x}a_{y} constant. In contrast, Tc is a non-monotonic function of the cross-section area for fixed P0P_{0}. In addition to the BEC cusp, the specific heat exhibits a set of maxima and minima. The minimum located at the highest temperature is a clear signal of the confinement effect which occurs when the boson wavelength is twice the cross-section side size. This confinement is amplified when the wall strength is increased until a dimensional crossover from 3D to 1D is produced. Some of these features in the specific heat obtained from this simple model can be related, qualitatively, to at least two different experimental situations: 4^4He adsorbed within the interstitial channels of a bundle of carbon nanotubes and superconductor-multistrand-wires Nb3_{3}Sn.Comment: 9 pages, 10 figures, submitte

    Plankton lattices and the role of chaos in plankton patchiness

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    Spatiotemporal and interspecies irregularities in planktonic populations have been widely observed. Much research into the drivers of such plankton patches has been initiated over the past few decades but only recently have the dynamics of the interacting patches themselves been considered. We take a coupled lattice approach to model continuous-in-time plankton patch dynamics, as opposed to the more common continuum type reaction-diffusion-advection model, because it potentially offers a broader scope of application and numerical study with relative ease. We show that nonsynchronous plankton patch dynamics (the discrete analog of spatiotemporal irregularity) arise quite naturally for patches whose underlying dynamics are chaotic. However, we also observe that for parameters in a neighborhood of the chaotic regime, smooth generalized synchronization of nonidentical patches is more readily supported which reduces the incidence of distinct patchiness. We demonstrate that simply associating the coupling strength with measurements of (effective) turbulent diffusivity results in a realistic critical length of the order of 100 km, above which one would expect to observe unsynchronized behavior. It is likely that this estimate of critical length may be reduced by a more exact interpretation of coupling in turbulent flows

    Elementary motor perseveration in early diagnosis of progressive supranuclear palsy

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    Three patients with progressive supranuclear palsy (PSP) with different symptoms at onset presented intense elementary motor perseverations before the appearance of the distinctive features of the illness. In elementary motor perseveration once an element of a movement has begun it is no longer inhibited at the right time and continues unchecked. Perseverations were observed in these patients during tests for dysdiadokokinesia, for reproduction of rhythmic structures and during the drawing of simple geometric shapes. Though this sign has not yet been described in PSP it is possible that an adequate search for its occurrence may show it to be an important sign for early diagnosis and an element for the clinical characterization of PSP
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