740 research outputs found

    Ultrassonografia duplex Doppler transcraniana em cães com hidrocefalia

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    Transcranial duplex Doppler ultrasound was performed in 32 conscious dogs presenting ventriculomegaly detected in B-mode, obtaining measures of lateral ventricles and resistance parameters of main cerebral arteries before and after 30 days of clinical treatment. The animals were distributed divided in two groups: group 1, dogs that presented remission or decrease of the neurological signs of the disease after clinical therapy; and group 2, dogs that displayed worsening of the neurological signs or clinical stability. The data were all presented in tables and were submitted to paired t test and to logistic regression models to evaluate the influence of the RI reduction on both groups. There was no significant influence of the variables in the B-mode. After the treatment, the mean resistive index (RI) was significantly lower for the group that presented clinical improvement. There was no significant difference of the mean RI reduction for the same artery when the right and left sides were compared. It could be concluded that transcranial duplex Doppler ultrasound is a method of cerebral hemodynamic assessment able to monitor more precisely the treatment of hydrocephalus in dogs and verify the responses.Foi realizada a ultrassonografia duplex Doppler transcraniana em 32 cães, conscientes, que apresentavam ventriculomegalia previamente detectada ao exame modo-B, para obter as medidas dos ventrículos laterais e os parâmetros de resistência das artérias cerebrais antes e depois de 30 dias de tratamento clínico. Os animais foram distribuídos em dois grupos: 1 - formado por cães que apresentaram remissão ou diminuição dos sinais clínicos após tratamento; 2 - por cães que apresentaram piora dos sinais neurológicos ou estabilidade do quadro clínico. Todos os dados foram dispostos em tabelas e submetidos ao teste t pareado e a modelos de regressão logística para avaliar a influência da redução do índice de resistividade (IR). Não foi observada influência das variáveis em modo-B. Após o tratamento, a média do IR foi significantemente menor para o grupo que apresentou melhora clínica; não houve diferença significativa da média de redução do IR para a mesma artéria quando comparados os lados direito e esquerdo. Concluiu-se que o duplex Doppler transcraniano é um métodos de avaliação hemodinâmica capaz de monitorar mais precisamente o tratamento da hidrocefalia em cães e verificar a resposta dos pacientes

    AS COURAÇAS E SEU PAPEL NO ESTUDO DA EVOLUÇÃO DO RELEVO, EM MARACAÍ/SP

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    O objetivo deste artigo é mostrar o papel das couraças como indicador da evolução do relevo, principalmente no que diz respeito ao desenvolvimento da rede de drenagem. As couraças ferruginosas teriam sido formadas concomitantemente às depressões fechadas, e com o rebaixamento do nível de base foram expostas. Atualmente, a maioria das couraças observadas está em áreas de depressões que foram capturadas pela rede de drenagem, constituindo-se como registros da evolução do relevo

    Infection By The Human Papillomavirus In Teenagers Sexually Active: Clinic And Subclinic Manifestations.

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    This research studies the association of the cervical condyloma with the intraepithelial neoplasia, during sex activity, pregnancy, diagnose methods, cytology and colposcopy in teenagers. The objective of this research is to study the propaedeutics for the uterine coli condyloma diagnose in a group of teenagers. For this purpose, we have studied 131 teenagers sexually active with ages between 14 and 19 years and presenting histologically confirmed uterine coli condyloma. Association with intraepithelial neoplasia, sexual activity duration, method of diagnose, pregnancy analysis, cytology and colposcopy results and association with vulva and vagina injuries were evaluated. The high association rate with condyloma and intraepithelial neoplasia after a short time of sexual activity and the none presence of macroscopic warts in the genital organs in 80% of cases presenting cervical condyloma, demonstrate that: a more careful investigation with colposcopy and biopsy of the inferior genitals of the women-teenagers sexually active is needed, when presenting modified cervical cytology.113494895

    Electromagnetic Response of Layered Superconductors with Broken Lattice Inversion Symmetry

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    We investigate the macroscopic effects of charge density waves (CDW) and superconductivity in layered superconducting systems with broken lattice inversion symmetry (allowing for piezoelectricity) such as two dimensional (2D) transition metal dichalcogenides (TMD). We work with the low temperature time dependent Ginzburg-Landau theory and study the coupling of lattice distortions and low energy CDW collective modes to the superconducting order parameter in the presence of electromagnetic fields. We show that superconductivity and piezoelectricity can coexist in these singular metals. Furthermore, our study indicates the nature of the quantum phase transition between a commensurate CDW phase and the stripe phase that has been observed as a function of applied pressure.Comment: 9 pages, 1 figure. Final version. Accepted in Phys.Rev.

    Bone Flap Management In Neurosurgery

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    Bone flap removal procedure is growing in frequency in neurosurgical practice. Decompressive craniotomy has gained more scientifical evidences of its therapeutical value in post-traumatic brain swelling, in cerebrovascular diseases and in brain edema non - responding to clinical treatment after elective surgeries. Bone flap destination after craniotomy has many possible fates. We present a literature review of bone flap management in neurosurgical practice: technical preservation of bone flaps (under the scalp, in the abdominal wall, frozen), when to remove the bone flap and what to do when it is dropped during the craniotomy or is infected.172133137Movassaghi, K., Ver Halen, J., Ganchi, P., Amin-Hanjani, S., Mesa, J., Yaremchuk, M.J., Cranioplasty with subcutaneously preserved autologous bone grafts (2006) Plast Reconstr Surg, 117 (1), pp. 202-206Hauptli, J., Segantini, P., New tissue preservation method for bone flaps following decompressive craniotomy (1980) Helv Chir Acta, 47 (1-2), pp. 121-124Tybor, K., Fortuniak, J., Komunski, P., Papiez, T., Andrzejak, S., Jaskólski, D., Supplementation of cranial defects by an autologous bone flap stored in the abdominal wall (2005) Neurol Neurochir Pol, 39 (3), pp. 220-224Josan, V.A., Sgouros, S., Walsh, A.R., Dover, M.S., Nishikawa, H., Hockley, A.D., Cranioplasty in children (2005) Childs Nerv Syst, 21 (3), pp. 200-204Flannery, T., McConnell, R.S., Cranioplasty: Why throw the bone flap out? (2001) Br J Neurosurg, 15 (6), pp. 518-520Krishnan, P., Bhattacharyya, A.K., Sil, K., De, R., Bone flap preservation after decompressive craniectomy - experience with 55 cases (2006) Neurol India, 54 (3), pp. 291-292Korfali, E., Aksoy, K., Preservation of craniotomy bone flaps under the scalp (1988) Surg Neurol, 30 (4), pp. 269-272Goel, A., Deogaonkar, M., Subgaleal preservation of calvarial flaps (1995) Surg Neurol, 44 (2), pp. 181-182. , Aug;, discussion 182-3Pasaoglu, A., Kurtsoy, A., Koc, R.K., Kontas, O., Akdemir, H., Öktem, I.S., Cranioplasty with bone flaps preserved under the scalp (1996) Neurosurg Rev, 19 (3), pp. 153-156Iwama, T., Yamada, J., Imai, S., Shinoda, J., Funakoshi, T., Sakai, N., The use of frozen autogenous bone flaps in delayed cranioplasty revisited (2003) Neurosurgery, 52 (3), pp. 591-596Winkler, P.A., Stummer, W., Linke, R., Krishnan, K.G., Tatsch, K., The influence of cranioplasty on postural blood flow regulation, cerebrovascular reserve capacity, and cerebral glucose metabolism (2000) Neurosurg Focus, 8 (1), pp. e9Matsuno, A., Tanaka, H., Iwamuro, H., Takanashi, S., Miyawaki, S., Nakashima, M., Analyses of the factors influencing bone graft infection after delayed cranioplasty (2006) Acta Neurochir (Wien), 148 (5), pp. 535-540Yacubian-Fernandes, A., Laronga, P.R., Coelho, R.A., Ducati, L.G., Silva, M.V., Prototyping as an alternative to cranioplasty using methylmethacrylate: Technical, 62 (3 B), pp. 865-868. , note. Arq Neuropsiquiatr 2004;Chiarini, L., Figurelli, S., Pollastri, G., Torcia, E., Ferrari, F., Albanese, M., Cranioplasty using acrylic material: A new technical procedure (2004) J Craniomaxillofac Surg, 32 (1), pp. 5-9Korinek, A.M., Risk factors for neurosurgical site infections after craniotomy: A prospective multicenter study of 2944 patients. The French Study Group of Neurosurgical Infections, the SEHP, and the C-CLIN Paris-Nord. Service Epidemiologie Hygiene et Prevention (1997) Neurosurgery, 41 (5), pp. 1073-1079Bruce, J.N., Bruce, S.S., Preservation of bone flaps in patients with postcraniotomy infections (2003) J Neurosurg, 98 (6), pp. 1203-1207Auguste, K.I., McDermott, M.W., Salvage of infected craniotomy bone flaps with the wash-in, wash-out indwelling antibiotic irrigation system. Technical note and case series of 12 patients (2006) J Neurosurg, 105 (4), pp. 640-644Jankowitz, B.T., Kondziolka, D.S., When the bone flap hits the floor (2006) Neurosurgery, 59 (3), pp. 585-59

    An Overall Evaluation Of The Resistance (r) And Pathogenesis-related (pr) Super Families In Soybean, As Compared With Medicago And Arabidopsis

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    Plants have the ability to recognize and respond to a multitude of pathogens, resulting in a massive reprogramming of the plant to activate defense responses including Resistance (R) and Pathogenesis-Related (PR) genes. Abiotic stresses can also activate PR genes and enhance pathogen resistance, representing valuable genes for breeding purposes. The present work offers an overview of soybean Rand PR genes present in the GENOSOJA (Brazilian Soybean Genome Consortium) platform, regarding their structure, abundance, evolution and role in the plant-pathogen metabolic pathway, as compared with Medicago and Arabidopsis. Searches revealed 3,065 R candidates (756 in Soybean, 1,142 in Medicago and 1,167 in Arabidopsis), and PR candidates matching to 1,261 sequences (310, 585 and 366 for the three species, respectively). The identified transcripts were also evaluated regarding their expression pattern in 65 libraries, showing prevalence in seeds and developing tissues. Upon consulting the Super SAGE libraries, 1,072 Rand 481 PR tags were identified in association with the different libraries. Multiple alignments were generated forXa21andPR-2genes, allowing inferences about their evolution. The results revealed interesting insights regarding the variability and complexity of defense genes in soybean, as compared with Medicago and Arabidopsis. © 2012, Sociedade Brasileira de Genética.35SUPPL.1260271Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., Walter, P., (2002) Molecular Biology of the Cell, p. 1616. , 4th edition. Garland Publishing Company, New York & LondonAltschul, S.F., Gish, W., Miller, W., Myers, E., Basic local alignment search tool (1990) J Mol Biol, 215, pp. 403-410Ashfield, T., Bocian, A., Held, D., Henk, A.D., Marek, L.F., Danesh, D., Penuela, S., Young, N.D., Genetic and physical localization of the soybean Rpg1-b disease resistance gene reveals a complex locus containing several tightly linked families of NBS-LRR genes (2003) Mol Plant Microbe Interact, 16, pp. 817-826Atici, O., Nalbantoglu, B., Antifreeze proteins in higher plants (2003) Phytochemistry, 64, pp. 1187-1196Barbosa-da-Silva, A., Wanderley-Nogueira, A.C., Silva, R.R.M., Belarmino, L.C., Soares-Cavalcanti, N.M., Benko-Iseppon, A.M., In silico survey of resistance (R) genes in Eucalyptus transcriptome (2005) Genet Mol Biol, 28, pp. 562-574Benko-Iseppon, A.M., Galdino, S.L., Calsa, T., Kido, E.A., Tossi, A., Belarmino, L.C., Crovella, S., Overview of plant antimicrobial peptides (2010) Curr Prot Pept Sci, 11, pp. 181-188Bent, A.F., Plant disease resistance genes: Function meets structure (1996) Plant Cell, 8, pp. 1751-1771Bolton, M., Primary metabolism and plant defense-Fuel for the fire (2009) Mol Plant Microbe Interact, 22, pp. 487-497Bonas, U., Anckerveken, G.V., Gene-for-gene interactions: Bacterial avirulence proteins specify plant disease resistance (1999) Curr Opin Plant Biol, 2, pp. 94-98Bonasera, J.M., Kim, J.F., Beer, S.V., PR genes of apple: Identification and expression in response to elicitors and inoculation with Erwinia amylovora (2006) BMC Plant Biol, 6, pp. 23-34Cannon, S.B., May, G.D., Jackson, S.A., Three sequenced legume genomes and many crop species: Rich opportunities for translational genomics (2009) Plant Physiol, 151, pp. 970-977Chester, K.S., The problem of acquired physiological immunity in plants (1933) Quart Rev Phytopathol, 42, pp. 185-209Dafny-Yelin, M., Tzfira, T., Delivery of multiple trans-genes to plant cells (2007) Plant Physiol, 145, pp. 1118-1128Dinesh-Kumar, S.P., Whitham, S., Choi, D., Hehl, R., Corr, C., Baker, B., Transposon tagging of tobacco mosaic virus resistance gene N:I its possible role in the TMV-N-mediated signal transduction pathway (1995) Proc Natl Acad Sci USA, 92, pp. 4175-4180Dixon, M.S., Jones, D.A., Keddie, J.S., Thomas, C.T., Harrison, K., Jones, J.D.G., The tomato Cf2 disease resistance locus comprises two functional genes encoding leucine rich repeats proteins (1996) Cell, 84, pp. 451-459Durrant, W.E., Dong, X., Systemic acquired resistance (2004) Annu Rev Plant Pathol, 42, pp. 185-209Eisen, M.B., Spellman, P.T., Brown, P.O., Botstein, B., Cluster analysis and display of genome-wide expression patterns (1998) Genetics, 25, pp. 14863-14868Ellis, J., Jones, D., Structure and function of proteins controlling strain-specific pathogen resistance in plants (2000) Curr Opin Plant Biol, 1, pp. 288-293Ellis, J., Lawrence, G.J., Finnegan, E.J., Anderson, P.A., Contrasting complexity of two rust resistance loci in flax (1995) Proc Natl Acad Sci USA, 92, pp. 4185-4188Ellis, J., Dodds, P., Pryor, T., Structure, function and evolution of plant disease resistance genes (2000) Curr Opin Plant Biol, 3, pp. 278-284Gaffney, T., Friedrich, L., Vernooij, B., Negrotto, D., Nye, G., Ukness, S., Ward, E., Kessman Hand Ryals, J., Requirementofsalicylic acid for the induction of systemic acquired resistance (1993) Science, 261, pp. 754-756Glombitza, S., Dubuis, P.-H., Thulke, O., Welzl, G., Bovet, L., Götz, M., Affenzeller, M., Asnaghi, C., Crosstalk and differential response to abiotic and biotic stressors reflected at the transcriptional level of effector genes from secondary metabolism (2004) Plant Mol Biol, 54, pp. 817-835Griffith, M., Yaish, M.W.F., Antifreeze proteins in overwintering plants: A tale of two activities (2004) Trends Plant Sci, 9, pp. 399-405Hammond-Kosack, K.E., Jones, J.D.G., Plant disease resistance genes (1997) Annu Rev Plant Physiol, 48, pp. 575-607Hon, W.C., Griffith, M., Mlynarz, A., Kwok, Y.C., Yang, D.S.C., Antifreeze proteins in winter rye are similar to pathogenesis-related proteins (1995) Plant Physiol, 109, pp. 879-889Hulbert, S.H., Webb, C.A., Smith, S.M., Sun, Q., Resistance gene complexes: Evolution and utilization (2001) Annu Rev Phytopathol, 39, pp. 285-312Joahal, G.S., Briggs, S.P., Reductase activity encodes by the Hm1 resistance gene in maize (1992) Science, 198, pp. 985-987Kanazin, V., Marek, L.F., Shoemaker, R.C., Resistance gene analogs are conserved and clustered in soybean (1996) Proc Natl Acad Sci USA, 93, pp. 11746-11750Kido, E.A., Barbosa, P.K., Ferreira Neto, J.C.R., Pandolfi, V., Houllou-Kido, L.M., Crovella, S., Benko-Iseppon, A.M., Identification of plant protein kinases in response to abiotic and biotic stresses using Super SAGE (2011) Curr Prot Pept Sci, 12, pp. 643-656Kitajima, S., Sato, F., Plant pathogenesis-related proteins: Molecular mechanisms of gene expression and protein function (1999) J Biochem, 125, pp. 1-8Lavin, M., Herendeen, P.S., Wojciechowski, M.F., Evolutionary rates analysis of Leguminosae implicates a rapid diversification of lineages during the tertiary (2005) Syst Biol, 54, pp. 575-594Lawrence, G.J., Finnegan, E.J., Ayliffe, M.A., Ellis, J.G., The L6 gene for flax rust resistance is related to the Arabidopsis bacterial resistance gene RPS2 and the tobacco viral resistance gene (1995) N. Plant Cell, 7, pp. 1195-1206Leubner-Metzger, G., β-1,3-glucanase gene expression in low-hydrated seeds as a mechanism for dormancy release during tobacco after-ripening (2005) Plant J, 41, pp. 133-145Li, L., He, H., Zhang, J., Wang, X., Bai, S., Stolc, V., Tongprasit, W., Deng, X.W., Transcriptional analysis of highly syntenic regions between Medicago truncatula and Glycine max using tiling microarrays (2008) Genome Biol, 9, pp. R57Libault, M., Farmer, A., Joshi, T., Takahashi, K., Langley, R.J., Franklin, L.D., He, J., Stacey, G., An integrated transcriptome atlas of the crop model Glycine max and its use in comparative analyses in plants (2010) Plant J, 63, pp. 86-99Liu, B., Zhang, S., Zhu, X., Yang, Q., Wu, S., Mei, M., Mauleon, R., Leung, H., Candidate defense genes as predictors of quantitative blast resistance in rice (2004) Mol Plant Microbe Int, 17, pp. 1146-1152Maisonneuve, B., Bellec, Y., Anderson, P., Michelmore, R.W., Rapid mapping of two genes for resistance to downy mildew from Lactuca serriola to existing clusters of resistance genes (1994) Theor Appl Genet, 89, pp. 96-104Matsumura, H., Kruger, D.H., Kahl, G., Terauchi, R., SuperSAGE: A modern platform for genome-wide quantitative transcript profiling (2008) Curr Pharm Biotechnol, 9, pp. 368-374Melotto, M., Coelho, M.F., Pedrosa-Harand, A., Kelly, J.D., Camargo, L.E., The anthracnose resistance locus Co-4 of common bean is located on chromosome 3 and contains putative disease resistance-related genes (2004) Theor Appl Genet, 109, pp. 690-699Metzler, M.C., Cutt, J.R., Klessig, D.F., Isolation and characterization of a gene encoding a PR-1 like protein from Arabidopsis thaliana (1991) Plant Physiol, 96, pp. 346-348Michelmore, R.W., Meyers, B.C., Clusters of resistance genes in plants evolve by divergent selection and a birth-and-death process (1998) Genome Res, 8, pp. 1113-1130Mindrinos, M., Katagiri, F., Yu, G.L., Ausubel, F.M., The Arabidopsis thaliana disease resistance gene encodes a protein containing a nucleotide-binding site and leucine rich repeats (1994) Cell, 78, pp. 1089-1099Mudge, J., Cannon, S.B., Kalo, P., Oldroyd, G.E., Roe, B.A., Town, C.D., Young, N.D., Highly syntenic regions in the genomes of soybean, Medicago truncatula and Arabidopsis thaliana (2005) BMC Plant Biol, 5, pp. e15Nanda, A.K., Andrio, E., Marino, D., Pauly, N., Dunand, C., Reactive Oxygen Species during plant-microorganism early interactions (2010) J Integr Plant Biol, 52, pp. 195-204Nurnberg, T., Brunner, F., Innate immunity in plants and animals: Emerging parallels between the recognition of general elicitors and pathogen-associated molecular patterns (2002) Curr Opin Plant Biol, 5, pp. 318-324Page, R.D., (1996) Comp Appl Biosci, 12, pp. 357-358Rayapati, P.J., Lee, M., Gregory, J.W., Wise, R.P., A linkage map of diploid Avena based on RFLP loci and a locus conferring resistance to nine isolates of Puccinia coronata var. 'avenae' (1994) Theor Appl Genet, 89, pp. 831-837Salmeron, J.M., Oldroyd, G.E.D., Romens, C.M.T., Scofield, S.R., Kim, H.S., Lavelle, D.T., Dahlbeck, D., Staskawicz, B.J., Tomato Prf is a member of the leucine rich repeats class of plant disease resistance genes and lies embedded within the Pto kinase gene cluster (1996) Cell, 86, pp. 123-133Shoemaker, R.C., Schlueter, J., Doyle, J.J., Paleopolyploidy and gene duplication in soybean and other legumes (2006) Curr Opin Plant Biol, 9, pp. 104-109Song, W.Y., Pi, L.Y., Wang, G.L., Gardner, J., Holsten, T., Ronald, P.C., Evolution of the rice Xa21 disease resistance genes family (1997) Plant Cell, 9, pp. 1279-1287Song, W.Y., Wang, G.L., Kim, H.S., Pi, L.Y., Gardner, J., Wang, B., Holsten, T., Fauquet, C., A receptor kinase-like protein encoded by the rice disease resistance gene Xa21 (1995) Science, 270, pp. 1804-1806Sparla, F., Rotino, L., Valgimigli, M.C., Pupillo, P., Trost, P., Systemic resistance induced by benzothisdizole in pear inoculated with the agent of fire blight (2004) Sci Hortic, 101, pp. 269-279Tamura, K., Dudley, J., Nei, M., Kumar, S., MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) software ver. 4.0 (2007) Mol Biol Evol, 24, pp. 1596-1599Tang, X., Xie, M., Kim, Y.J., Zhou, J., Klessing, D.F., Martin, G.B., Overexpression of Pto activates defense responses and confers broad resistance (1999) Plant Cell, 11, pp. 15-29Thiel, T., Graner, A., Waugh, R., Grosse, I., Close, T.J., Stein, N., Evidence and evolutionary of ancient whole-genome duplication in barley predating the divergence from rice (2009) BMC Evol Biol, 9, pp. 209-227Tornero, P., Gadea, J., Conejero, V., Vera, P., Two PR-1 genes from tomato are differentially regulated and reveal a novel mode of expression for a pathogenesis-related gene during the hypersensitive response and development (1997) Plant Microbe Interact, 10, pp. 624-634Van-Loon, L.C., Geraats, B.P.J., Linthorst, H.J.M., Ethylene as a modulator of disease resistance in plants (2006) Trends Plant Sci, 11, pp. 184-191Van-Loon, L.C., Pierpoint, W.S., Boller, T., Conejero, V., Recommendations for naming plant pathogenesis-related proteins (1999) Plant Mol Biol Rep, 12, pp. 245-264Velazhahan, R., Muthukrishnan, S., Transgenic tobacco plants constitutively overexpressing a rice thaumatin-like protein (PR-5) show enhanced resistance to Alternaria alternata (2003) Plant Biol, 47, pp. 347-354Vergne, E., Grand, X., Ballini, R., Chalvon, V., Saindrenan, P., Tharreau, D., Nottéghem, J.-L., Morel, J.-B., Preformed expression of defense is a hallmark of partial resistance to rice blast fungal pathogen Magnaporthe oryzae (2010) BMC Plant Biol, 10, pp. e206Wanderley-Nogueira, A.C., Mota, N., Lima-Morais, D., Silva, L.C.B., Silva, A.B., Benko-Iseppon, A.M., Abundance and diversity of resistance (R) genes in the sugarcane trans-criptome (2007) Genet Mol Res, 6, pp. 866-889Wang, G.L., Holsten, T.E., Song, W.Y., Wang, H.P., Ronald, P.C., Construction of a rice bacterial artificial chromosome library and identification of clones linked to the Xa21 disease resistance locus (1995) Plant J, 7, pp. 525-533Wendell, J., Genome evolution in polyploids (2000) Plant Mol Biol, 42, pp. 225-249Weng, J.K., Banks, J.A., Chapple, C., Parallels in lignin biosynthesis: A study in Selaginella moellendorffii reveals convergence across 400 million years of evolution (2008) Comm Int Biol, 1, pp. 20-22Wilkstrom, N., Savolainen, V., Chase, M.W., Evolution of the angiosperms: Calibrating the family tree (2001) Proc Soc Biol Sci, 268, pp. 2211-2220Zeier, J., Pink, B., Mueller, M.J., Berger, S., Light conditions influence specific defense responses in incompatible plant-pathogen interactions: Uncoupling systemic resistance from salicylic acid and PR-1 accumulation (2004) Planta, 219, pp. 673-68

    Phonon-mediated anisotropic superconductivity in the Y and Lu nickel borocarbides

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    We present scanning tunneling spectroscopy and microscopy measurements at low temperatures in the borocarbide materials RNi2B2C (R=Y, Lu). The characteristic strong coupling structure due to the pairing interaction is unambiguously resolved in the superconducting density of states. It is located at the superconducting gap plus the energy corresponding to a phonon mode identified in previous neutron scattering experiments. These measurements also show that this mode is coupled to the electrons through a highly anisotropic electron-phonon interaction originated by a nesting feature of the Fermi surface. Our experiments, from which we can extract a large electron-phonon coupling parameter lambda (between 0.5 and 0.8), demonstrate that this anisotropic electron-phonon coupling has an essential contribution to the pairing interaction. The tunneling spectra show an anisotropic s-wave superconducting gap function.Comment: 5 pages, 3 figure
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