92,728 research outputs found

    The management of advanced hepatocellular carcinoma: are we making progress in the era of targeted therapy?

    Get PDF

    Triclocarban Influences Antibiotic Resistance and Alters Anaerobic Digester Microbial Community Structure

    Get PDF
    Triclocarban (TCC) is one of the most abundant organic micropollutants detected in biosolids. Lab-scale anaerobic digesters were amended with TCC at concentrations ranging from the background concentration of seed biosolids (30 mg/kg) to toxic concentrations of 850 mg/kg to determine the effect on methane production, relative abundance of antibiotic resistance genes, and microbial community structure. Additionally, the TCC addition rate was varied to determine the impacts of acclimation time. At environmentally relevant TCC concentrations (max detect = 440 mg/kg), digesters maintained function. Digesters receiving 450 mg/kg of TCC maintained function under gradual TCC addition, but volatile fatty acid concentrations increased, pH decreased, and methane production ceased when immediately fed this concentration. The concentrations of the mexB gene (encoding for a multidrug efflux pump) were higher with all concentrations of TCC compared to a control, but higher TCC concentrations did not correlate with increased mexB abundance. The relative abundance of the gene tet(L) was greater in the digesters that no longer produced methane, and no effect on the relative abundance of the class 1 integron integrase encoding gene (intI1) was observed. Illumina sequencing revealed substantial community shifts in digesters that functionally failed from increased levels of TCC. More subtle, yet significant, community shifts were observed in digesters amended with TCC levels that did not inhibit function. This research demonstrates that TCC can select for a multidrug resistance encoding gene in mixed community anaerobic environments, and this selection occurs at concentrations (30 mg/kg) that can be found in full-scale anaerobic digesters (U.S. median concentration = 22 mg/kg, mean = 39 mg/kg)

    The Integral Role of Tulsa Community College in the Mathematics and Science Preparation of Prospective Teachers

    Get PDF
    The role of the two-year college in the mathematics and science preparation of prospective teachers is fast becoming a prominent inļ¬‚uence on teacher education programs across the country. This article describes the multifaceted role of Tulsa Community College (TCC), Tulsa, Oklahoma, in the preparation of prospective teachers in math and science. Since 1987 Tulsa Community College has hosted many events, activities, and programs aimed at the sciences. TCC activities/programs have focused on five areas: (1) preservice and inservice preparation; (2) summer teacher institutes supported by state and federal grants; (3) recruitment and emphasis on underrepresented groups; (4) parateacher associate degree/certiļ¬cation program; (5) workshops, seminars, and other activities. This article presents the TCC role by examining these five areas in terms of assessment of successful strategies, signiļ¬cant collaborations, and impact of the TCC teacher preparation activities on students and the community. Also presented are the implications for future TCC programs and the TCC vision for the math and science preparation of prospective teachers for the 21st century and beyond

    Development of timber concrete composite (TCC) beam with post-tensioning

    Get PDF
    Post-tensioning is a method of reinforcing (strengthening) concrete or other materials with high-strength steel strands or bars. The timber type that is used in all researches is the engineering timber products laminated veneer lumber (LVL) and glue-laminated wood (Glu-Lam), while avoiding using natural timber due to its propertiesā€™ variety. More recent improvement is using post-tensioning technique for the engineering timber products. The main material in this research is natural Kempas timber. The primary objective of this research is to develop of a method of timber beam post-tensioning and proposed empirical Equation to predict the bending moment capacity for timber beam and timber concrete composite beam through the bending strength properties. The experimental program is divided into 3 major phases across the duration of this study. Phase A present post-tensioning method, this phase indicate two methods of postļæ½tensioning ā€œforced bending jacking PT-Bā€ and ā€œpre-stressing jacking PT-Jā€. Phase B present timber bending performance in term of (strength and failure behavior), include 4 point bending tests for timber beams and post-tensioning timber beams, the timber beam size (40 mm x90 mm x1200 mm) the tendon type is threaded rod bar with two colors silver color (9.4 mm) and black color (8.85 mm) . Phase C involved post-tensioned timber concrete composite beam (the concrete layer is 65 mm) Bending Performance. From the test results for the two methods of pre-stressing it is clear that pre-stressing Jacking give higher residual deflection 98.2 % for silver color rod bar against black color with 88.8 % residual deflection. So this type of rod bar (silver color with long nut coupling) is the more efficient in use due to the high contact friction surface area for long coupling nut. The bending tests of post-tensioned beams show the range of bending strength capacity increasing 12 % to 46 %. There were three types of failure is tensile, compression and splitting shear failure depending on the timber quality (degree of natural effect). The PT-TCC give bending strength increment according to degree of composite action 500 mm, 100 mm and 70 mm screw spacing is 68 %, 85 % and 150 % respectively. The empirical Equation derived for bending moment capacity for postļæ½tensioning Kempas timber beam is basically depended on the experimental relation between vertical deflection and rod bar strain. The empirical Equation shows 3.06 kNvi constant difference for the theoretical equation and the equation form is PTempirical = 8EIāˆ† eL2 āˆ’ 3.06. In the case of PT-TCC the proposed equation depend on the concept of connector slip modulus. A three paths of estimation were discussed depend on push out test slip modulus. The gamma design method show that the slip modulus of pushout test gives a proper estimation in the case of PT-TCC specimens bending strength design

    Mutations in SPG11, encoding spatacsin, are a major cause of spastic paraplegia with thin corpus callosum.

    Get PDF
    Autosomal recessive hereditary spastic paraplegia (ARHSP) with thin corpus callosum (TCC) is a common and clinically distinct form of familial spastic paraplegia that is linked to the SPG11 locus on chromosome 15 in most affected families. We analyzed 12 ARHSP-TCC families, refined the SPG11 candidate interval and identified ten mutations in a previously unidentified gene expressed ubiquitously in the nervous system but most prominently in the cerebellum, cerebral cortex, hippocampus and pineal gland. The mutations were either nonsense or insertions and deletions leading to a frameshift, suggesting a loss-of-function mechanism. The identification of the function of the gene will provide insight into the mechanisms leading to the degeneration of the corticospinal tract and other brain structures in this frequent form of ARHSP

    Hamiltonian of Tensionless Strings with Tensor Central Charge Coordinates

    Full text link
    A new class of twistor-like string models in four-dimensional space-time extended by the addition of six tensorial central charge (TCC) coordinates zmnz_{mn} is studied. The Hamiltonian of tensionless string in the extended space-time is derived and its symmetries are investigated. We establish that the string constraints reduce the number of independent TCC coordinates zmnz_{mn} to one real effective coordinate which composes an effective 5-dimensional target space together with the xmx^{m} coordinates. We construct the P.B. algebra of the first class constraints and discover that it coincides with the P.B. algebra of tensionless strings. The Lorentz covariant antisymmetric Dirac C^\hat{\mathbf C}-matrix of the P.B. of the second class constraints is constructed and its algebraic structure is further presented.Comment: 18 pages, Latex, no figure
    • ā€¦