Effect Of Post Type And Restorative Techniques On The Strain And Fracture Resistance Of Flared Incisor Roots

Restoring flared endodontically treated teeth continues to be a challenge for clinicians. This study evaluated the effect of post types and restorative techniques on the strain, fracture resistance, and fracture mode of incisors with weakened roots. One hundred five endodontically treated bovine incisors roots (15 mm) were divided into 7 groups (n=15). The two control groups were (C) intact roots restored with Cpc (cast posts and core) or Gfp (glass fiber posts). The five experimental groups were (F) flared roots restored with GfpAp (Gfp associated with accessory glass fiber posts), GfpRc (anatomic Gfp, relined with composite resin), and GfpRcAp (anatomized Gfp with resin and accessory glass fiber posts). All teeth were restored with metal crowns. Mechanical fatigue was performed with 3x10 5/50 N. Specimens were loaded at 45°, and the strain values (μS) were obtained on root buccal and proximal surfaces. Following that, the fracture resistance (N) was measured. One-way ANOVA and Tukey's HSD tests (α=0.05) were applied, and failure mode was checked. No significant difference in strain values among the groups was found. Cpc presented lower fracture resistance and more catastrophic failures in flared roots. Gfp associated with composite resin or accessory glass fiber posts seems to be an effective method to improve the biomechanical behavior of flared roots.223230237Coelho, C.S., Biffi, J.C., Silva, G.R., Abrahão, A., Campos, R.E., Soares, C.J., Finite element analysis of weakened roots restored with composite resin and posts (2009) Dent Mater J, 28, pp. 671-678Teixeira, C.S., Silva-Sousa, Y.T., Sousa-Neto, M.D., Bond strength of fiber posts to weakened roots after resin restoration with different light-curing times (2009) J Endod, 35, pp. 1034-1039Zogheib, L.V., Pereira, J.R., do Valle, A.L., de Oliveira, J.A., Pegoraro, L.F., Fracture resistance of weakened roots restored with composite resin and glass fiber post (2008) Braz Dent J, 19, pp. 329-333Marchi, G.M., Mitsui, F.H., Cavalcanti, A.N., Effect of remaining dentine structure and thermal-mechanical aging on the fracture resistance of bovine roots with different post and core systems (2008) Int Endod J, 41, pp. 969-976da Silveira, T.C., Santos, F.M.C., Silva-Sousa, Y.T., de Sousa-Neto, M.D., Interfacial evaluation of experimentally weakened roots restored with adhesive materials and fibre posts: An SEM analysis (2008) J Dent, 36, pp. 672-682Moosavi, H., Maleknejad, F., Kimyai, S., Fracture resistance of endodontically-treated teeth restored using three root- reinforcement methods (2008) J Contemp Dent Pract, 9, pp. 30-37Bonfante, G., Kaizer, O.B., Pegoraro, L.F., do Valle, A.L., Fracture strength of teeth with flared root canals restored with glass fibre posts (2007) Int Dent J, 57, pp. 153-160Santos, A.F., Meira, J.B., Tanaka, C.B., Xavier, T.A., Ballester, R.Y., Lima, R.G., Can fiber posts increase root stresses and reduce fracture? (2010) J Dent Res, 89, pp. 587-591da Silva, N.R., Raposo, L.H., Versluis, A., Fernandes-Neto, A.J., Soares, C.J., The effect of post, core, crown type, and ferrule presence on the biomechanical behavior of endodontically treated bovine anterior teeth (2010) J Prosthet Dent, 104, pp. 306-317Silva, N.R., Castro, C.G., Santos-Filho, P.C., Silva, G.R., Campos, R.E., Soares, P.V., Influence of different post design and composition on stress distribution in maxillary central incisor: Finite element analysis (2009) Indian J Dent Res, 20, pp. 153-158Santos-Filho, P.C., Castro, C.G., Silva, G.R., Campos, R.E., Soares, C.J., Effects of post system and length on the strain and fracture resistance of root filled bovine teeth (2008) Int Endod J, 41, pp. 493-501Soares, C.J., Castro, C.G., Santos, F.P.C., Soares, P.V., Magalhaes, D., Martins, L.R., Two-dimensional FEA of dowels of different compositions and external surface configurations (2009) J Prosthodont, 18, pp. 36-42Macedo, V.C., de Faria, S.A.L., Martins, L.R., Effect of cement type, relining procedure, and length of cementation on pull-out bond strength of fiber posts (2010) J Endod, 36, pp. 1543-1546Leitune, V.C., Collares, F.M., Werner, S.S.M., Influence of chlorhexidine application at longitudinal push-out bond strength of fiber posts (2010) Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 110, pp. 77-81Novais, V.R., Quagliatto, P.S., Bona, A.D., Correr-Sobrinho, L., Soares, C.J., Flexural modulus, flexural strength, and stiffness of fiber-reinforced posts (2009) Indian J Dent Res, 20, pp. 277-281Marchi, G.M., Paulillo, L.A., Pimenta, L.A., de Lima, F.A., Effect of different filling materials in combination with intraradicular posts on the resistance to fracture of weakened roots (2003) J Oral Rehabil, 30, pp. 623-629Soares, C.J., Pizi, E.C., Fonseca, R.B., Martins, L.R., Influence of root embedment material and periodontal ligament simulation on fracture resistance tests (2005) Braz Oral Res, 19, pp. 11-16Huysmans, M.C., Peters, M.C., van der Varst, P.G., Plasschaert, A.J., Failure behaviour of fatigue-tested post and cores (1993) Int Endod J, 26, pp. 294-300Soares, P.V., Santos-Filho, P.C., Gomide, H.A., Araujo, C.A., Martins, L.R., Soares, C.J., Influence of restorative technique on the biomechanical behavior of endodontically treated maxillary premolars. Part II: Strain measurement and stress distribution (2008) J Prosthet Dent, 99, pp. 114-122Kishen, A., Kumar, G.V., Chen, N.N., Stress-strain response in human dentine: Rethinking fracture predilection in post-core restored teeth (2004) Dent Traumatol, 20, pp. 90-10

Global conservation prioritization areas in three dimensions of crocodilian diversity

Lourenço-De-Moraes, R., Campos, F. S., Cabral, P., Silva-Soares, T., Nobrega, Y. C., Covre, A. C., & França, F. G. R. (2023). Global conservation prioritization areas in three dimensions of crocodilian diversity. Scientific Reports, 13(1), 1-13. [2568 ]. https://doi.org/10.1038/s41598-023-28413-6. --- Funding: This work was supported by the 715 Portuguese Foundation for Science and Technology (FCT), under the project - 716 UIDB/04152/2020 - Information Management Research Center (MagIC/NOVA IMS), 717 and the European Union-Next Generation EU. This study was financed in part by the 718 CAPES - Finance Code 001.Crocodilians are a taxonomic group of large predators with important ecological and evolutionary benefits for ecosystem functioning in the face of global change. Anthropogenic actions affect negatively crocodilians' survival and more than half of the species are threatened with extinction worldwide. Here, we map and explore three dimensions of crocodilian diversity on a global scale. To highlight the ecological importance of crocodilians, we correlate the spatial distribution of species with the ecosystem services of nutrient retention in the world. We calculate the effectiveness of global protected networks in safeguarding crocodilian species and provide three prioritization models for conservation planning. Our results show the main hotspots of ecological and evolutionary values are in southern North, Central and South America, west-central Africa, northeastern India, and southeastern Asia. African species have the highest correlation to nutrient retention patterns. Twenty-five percent of the world's crocodilian species are not significantly represented in the existing protected area networks. The most alarming cases are reported in northeastern India, eastern China, and west-central Africa which include endangered species with low or non-significant representation in the protected area networks. Our highest conservation prioritization model targets southern North America, east-central Central America, northern South America, west-central Africa, northeastern India, eastern China, southern Laos, Cambodia, and some points in southeastern Asia. Our research provides a global prioritization scheme to protect multiple dimensions of crocodilian diversity for achieving effective conservation outcomes.publishersversionpublishe

Rare Decays of \Lambda_b->\Lambda + \gamma and \Lambda_b ->\Lambda + l^{+} l^{-} in the Light-cone Sum Rules

Within the Standard Model, we investigate the weak decays of $\Lambda_b \to \Lambda + \gamma$ and $\Lambda_b \to \Lambda + l^{+} l^{-}$ with the light-cone sum rules approach. The higher twist distribution amplitudes of $\Lambda$ baryon to the leading conformal spin are included in the sum rules for transition form factors. Our results indicate that the higher twist distribution amplitudes almost have no influences on the transition form factors retaining the heavy quark spin symmetry, while such corrections can result in significant impacts on the form factors breaking the heavy quark spin symmetry. Two phenomenological models (COZ and FZOZ) for the wave function of $\Lambda$ baryon are also employed in the sum rules for a comparison, which can give rise to the form factors approximately 5 times larger than that in terms of conformal expansion. Utilizing the form factors calculated in LCSR, we then perform a careful study on the decay rate, polarization asymmetry and forward-backward asymmetry, with respect to the decays of $\Lambda_b \to \Lambda \gamma$, $\Lambda l^{+}l^{-}$.Comment: 38 pages, 15 figures, some typos are corrected and more references are adde

Demographic reconstruction from ancient DNA supports rapid extinction of the great auk

The great auk was once abundant and distributed across the North Atlantic. It is now extinct, having been heavily exploited for its eggs, meat, and feathers. We investigated the impact of human hunting on its demise by integrating genetic data, GPS-based ocean current data, and analyses of population viability. We sequenced complete mitochondrial genomes of 41 individuals from across the species’ geographic range and reconstructed population structure and population dynamics throughout the Holocene. Taken together, our data do not provide any evidence that great auks were at risk of extinction prior to the onset of intensive human hunting in the early 16th century. In addition, our population viability analyses reveal that even if the great auk had not been under threat by environmental change, human hunting alone could have been sufficient to cause its extinction. Our results emphasise the vulnerability of even abundant and widespread species to intense and localised exploitation

Produção e valor nutritivo da forragem de capim-elefante em dois sistemas de produção.

Esta pesquisa foi realizada com o objetivo de avaliar a produção e o valor nutritivo da forragem de capimelefante cultivado em sistemas convencional e agroecológico. No sistema convencional, o capim-elefante foi estabelecido em cultivo exclusivo, em linhas com espaçamento de 1,4 m e, no sistema agroecológico, em linhas afastadas 3 m. Nas entrelinhas, estabeleceu-se azevém no período hibernal para desenvolvimento de espécies de crescimento espontâneo no período estival. Avaliaram-se a massa, a produção e a composição botânica e estrutural da forragem e a carga animal. Amostras de simulação de pastejo foram coletadas para determinação dos teores de proteína bruta e fibra em detergente neutro e da digestibilidade in vitro da matéria seca e matéria orgânica. O delineamento experimental foi o inteiramente casualizado com dois tratamentos (sistemas convencional e agroecológico) e duas repetições (piquetes). Valores mais elevados para massa de forragem, produção de forragem, taxa de acúmulo diário e carga animal foram observados no sistema convencional. A relação folha:colmo foi similar entre os sistemas. Valor mais elevado de proteína bruta foi observado no sistema agroecológico. O capim-elefante sob manejo convencional apresenta maior produção de forragem, com menores teores de proteína bruta. O sistema agroecológico apresenta melhor distribuição da produção de forragem no decorrer do ano

Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters

Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV

The Lambda(b) differential production cross section and the cross section ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Lambda(b) decays reconstructed in the exclusive final state J/Psi Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and Lambda to proton pion, using a data sample corresponding to an integrated luminosity of 1.9 inverse femtobarns. The product of the cross section times the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls faster than that of b mesons. The measured value of the cross section times the branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06 +/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are statistical and systematic, respectively.Comment: Submitted to Physics Letters

Search for new physics in events with opposite-sign leptons, jets, and missing transverse energy in pp collisions at sqrt(s) = 7 TeV

A search is presented for physics beyond the standard model (BSM) in final states with a pair of opposite-sign isolated leptons accompanied by jets and missing transverse energy. The search uses LHC data recorded at a center-of-mass energy sqrt(s) = 7 TeV with the CMS detector, corresponding to an integrated luminosity of approximately 5 inverse femtobarns. Two complementary search strategies are employed. The first probes models with a specific dilepton production mechanism that leads to a characteristic kinematic edge in the dilepton mass distribution. The second strategy probes models of dilepton production with heavy, colored objects that decay to final states including invisible particles, leading to very large hadronic activity and missing transverse energy. No evidence for an event yield in excess of the standard model expectations is found. Upper limits on the BSM contributions to the signal regions are deduced from the results, which are used to exclude a region of the parameter space of the constrained minimal supersymmetric extension of the standard model. Additional information related to detector efficiencies and response is provided to allow testing specific models of BSM physics not considered in this paper.Comment: Replaced with published version. Added journal reference and DO