5,967 research outputs found

    Stationary motion of a self gravitating toroidal incompressible liquid layer

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    We consider an incompressible fluid contained in a toroidal stratum which is only subjected to Newtonian self-attraction. Under the assumption of infinitesimal tickness of the stratum we show the existence of stationary motions during which the stratum is approximatly a round torus (with radii r, R and R>>r) that rotates around its axis and at the same time rolls on itself. Therefore each particle of the stratum describes an helix-like trajectory around the circumference of radius R that connects the centers of the cross sections of the torus

    Braces for idiopathic scoliosis in adolescents.

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    BACKGROUND Idiopathic scoliosis is a three-dimensional deformity of the spine. The most common form is diagnosed in adolescence. While adolescent idiopathic scoliosis (AIS) can progress during growth and cause a surface deformity, it is usually not symptomatic. However, in adulthood, if the final spinal curvature surpasses a certain critical threshold, the risk of health problems and curve progression is increased. OBJECTIVES To evaluate the efficacy of bracing for adolescents with AIS versus no treatment or other treatments, on quality of life, disability, pulmonary disorders, progression of the curve, and psychological and cosmetic issues. SEARCH METHODS We searched CENTRAL, MEDLINE, EMBASE, five other databases, and two trials registers up to February 2015 for relevant clinical trials. We also checked the reference lists of relevant articles and conducted an extensive handsearch of grey literature. SELECTION CRITERIA Randomized controlled trials (RCTs) and prospective controlled cohort studies comparing braces with no treatment, other treatment, surgery, and different types of braces for adolescent with AIS. DATA COLLECTION AND ANALYSIS We used standard methodological procedures expected by The Cochrane Collaboration. MAIN RESULTS We included seven studies (662 participants). Five were planned as RCTs and two as prospective controlled trials. One RCT failed completely, another was continued as an observational study, reporting also the results of the participants that had been randomized.There was very low quality evidence from one small RCT (111 participants) that quality of life (QoL) during treatment did not differ significantly between rigid bracing and observation (mean difference (MD) -2.10, 95% confidence interval (CI) -7.69 to 3.49). There was very low quality evidence from a subgroup of 77 adolescents from one prospective cohort study showing that QoL, back pain, psychological, and cosmetic issues did not differ significantly between rigid bracing and observation in the long term (16 years).Results of the secondary outcomes showed that there was low quality evidence that rigid bracing compared with observation significantly increased the success rate in 20° to 40° curves at two years' follow-up (one RCT, 116 participants; risk ratio (RR) 1.79, 95% CI 1.29 to 2.50). There was low quality evidence that elastic bracing increased the success rate in 15° to 30° curves at three years' follow-up (one RCT, 47 participants; RR 1.88, 95% CI 1.11 to 3.20).There is very low quality evidence from two prospective cohort studies with a control group that rigid bracing increases the success rate (curves not evolving to 50° or above) at two years' follow-up (one study, 242 participants; RR 1.50, 95% CI 1.19 to 1.89) and at three years' follow-up (one study, 240 participants; RR 1.75, 95% CI 1.42 to 2.16). There was very low quality evidence from a prospective cohort study (57 participants) that very rigid bracing increased the success rate (no progression of 5° or more, fusion, or waiting list for fusion) in adolescents with high degree curves (above 45°) (one study, 57 adolescents; RR 1.79, 95% CI 1.04 to 3.07 in the intention-to-treat (ITT) analysis).There was low quality evidence from one RCT that a rigid brace was more successful than an elastic brace at curbing curve progression when measured in Cobb degrees in low degree curves (20° to 30°), with no significant differences between the two groups in the subjective perception of daily difficulties associated with wearing the brace (43 girls; risk of success at four years' follow-up: RR 1.40, 1.03 to 1.89). Finally, there was very low quality evidence from one RCT (12 participants) that a rigid brace with a pad pressure control system is no better than a standard brace in reducing the risk of progression.Only one prospective cohort study (236 participants) assessed adverse events: neither the percentage of adolescents with any adverse event (RR 1.27, 95% CI 0.96 to 1.67) nor the percentage of adolescents reporting back pain, the most common adverse event, were different between the groups (RR 0.72, 95% CI 0.47 to 1.10). AUTHORS' CONCLUSIONS Due to the important clinical differences among the studies, it was not possible to perform a meta-analysis. Two studies showed that bracing did not change QoL during treatment (low quality), and QoL, back pain, and psychological and cosmetic issues in the long term (16 years) (very low quality). All included papers consistently showed that bracing prevented curve progression (secondary outcome). However, due to the strength of evidence (from low to very low quality), further research is very likely to have an impact on our confidence in the estimate of effect. The high rate of failure of RCTs demonstrates the huge difficulties in performing RCTs in a field where parents reject randomization of their children. This challenge may prevent us from seeing increases in the quality of the evidence over time. Other designs need to be implemented and included in future reviews, including 'expertise-based' trials, prospective controlled cohort studies, prospective studies conducted according to pre-defined criteria such as the Scoliosis Research Society (SRS) and the international Society on Scoliosis Orthopedic and Rehabilitation Treatment (SOSORT) criteria. Future studies should increase their focus on participant outcomes, adverse effects, methods to increase compliance, and usefulness of physiotherapeutic scoliosis specific exercises added to bracing

    Shilnikov Lemma for a nondegenerate critical manifold of a Hamiltonian system

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    We prove an analog of Shilnikov Lemma for a normally hyperbolic symplectic critical manifold MH1(0)M\subset H^{-1}(0) of a Hamiltonian system. Using this result, trajectories with small energy H=μ>0H=\mu>0 shadowing chains of homoclinic orbits to MM are represented as extremals of a discrete variational problem, and their existence is proved. This paper is motivated by applications to the Poincar\'e second species solutions of the 3 body problem with 2 masses small of order μ\mu. As μ0\mu\to 0, double collisions of small bodies correspond to a symplectic critical manifold of the regularized Hamiltonian system

    Targeted knock-down of miR21 primary transcripts using snoMEN vectors induces apoptosis in human cancer cell lines

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    We have previously reported an antisense technology, 'snoMEN vectors', for targeted knock-down of protein coding mRNAs using human snoRNAs manipulated to contain short regions of sequence complementarity with the mRNA target. Here we characterise the use of snoMEN vectors to target the knock-down of micro RNA primary transcripts. We document the specific knock-down of miR21 in HeLa cells using plasmid vectors expressing miR21-targeted snoMEN RNAs and show this induces apoptosis. Knock-down is dependent on the presence of complementary sequences in the snoMEN vector and the induction of apoptosis can be suppressed by over-expression of miR21. Furthermore, we have also developed lentiviral vectors for delivery of snoMEN RNAs and show this increases the efficiency of vector transduction in many human cell lines that are difficult to transfect with plasmid vectors. Transduction of lentiviral vectors expressing snoMEN targeted to pri-miR21 induces apoptosis in human lung adenocarcinoma cells, which express high levels of miR21, but not in human primary cells. We show that snoMEN-mediated suppression of miRNA expression is prevented by siRNA knock-down of Ago2, but not by knock-down of Ago1 or Upf1. snoMEN RNAs colocalise with Ago2 in cell nuclei and nucleoli and can be co-immunoprecipitated from nuclear extracts by antibodies specific for Ago2

    Measurement of CP Asymmetries and Branching Fractions in Charmless Two-Body B-Meson Decays to Pions and Kaons

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    We present improved measurements of CP-violation parameters in the decays B0π+πB^0 \to \pi^+ \pi^-, B0K+πB^0 \to K^+ \pi^-, and B0π0π0B^0 \to \pi^0 \pi^0, and of the branching fractions for B0π0π0B^0 \to \pi^0 \pi^0 and B0K0π0B^0 \to K^0 \pi^0. The results are obtained with the full data set collected at the Υ(4S)\Upsilon(4S) resonance by the BABAR experiment at the PEP-II asymmetric-energy BB factory at the SLAC National Accelerator Laboratory, corresponding to 467±5467 \pm 5 million BBˉB\bar B pairs. We find the CP-violation parameter values and branching fractions Sπ+π=0.68±0.10±0.03,Cπ+π=0.25±0.08±0.02,AKπ+=0.107±0.0160.004+0.006,Cπ0π0=0.43±0.26±0.05,Br(B0π0π0)=(1.83±0.21±0.13)×106,Br(B0K0π0)=(10.1±0.6±0.4)×106, S_{\pi^+\pi^-} = -0.68 \pm 0.10 \pm 0.03, C_{\pi^+\pi^-} = -0.25 \pm 0.08 \pm 0.02, A_{K^-\pi^+} = -0.107 \pm 0.016 ^{+0.006}_{-0.004}, C_{\pi^0\pi^0} = -0.43 \pm 0.26 \pm 0.05, Br(B^0 \to \pi^0 \pi^0) = (1.83 \pm 0.21 \pm 0.13) \times 10^{-6}, Br(B^0 \to K^0 \pi^0) = (10.1 \pm 0.6 \pm 0.4) \times 10^{-6}, where in each case, the first uncertainties are statistical and the second are systematic. We observe CP violation with a significance of 6.7 standard deviations for B0π+πB^0 \to\pi^+\pi^- and 6.1 standard deviations for B0K+πB^0 \to K^+ \pi^-, including systematic uncertainties. Constraints on the Unitarity Triangle angle α\alpha are determined from the isospin relations among the BππB \to \pi\pi rates and asymmetries. Considering only the solution preferred by the Standard Model, we find α\alpha to be in the range [71,109][71^\circ,109^\circ] at the 68% confidence level.Comment: 18 pages, 11 postscript figures, submitted to Phys. Rev.

    Measurement of the Longitudinal Spin Transfer to Lambda and Anti-Lambda Hyperons in Polarised Muon DIS

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    The longitudinal polarisation transfer from muons to lambda and anti-lambda hyperons, D_LL, has been studied in deep inelastic scattering off an unpolarised isoscalar target at the COMPASS experiment at CERN. The spin transfers to lambda and anti-lambda produced in the current fragmentation region exhibit different behaviours as a function of x and xF . The measured x and xF dependences of D^lambda_LL are compatible with zero, while D^anti-lambda_LL tends to increase with xF, reaching values of 0.4 - 0.5. The resulting average values are D^lambda_LL = -0.012 +- 0.047 +- 0.024 and D^anti-lambda_LL = 0.249 +- 0.056 +- 0.049. These results are discussed in the frame of recent model calculations.Comment: 13 pages, 7 figure

    Search for lepton-number violating processes in B+ -> h- l+ l+ decays

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    We have searched for the lepton-number violating processes B+ -> h- l+ l+ with h- = K-/pi- and l+ = e+/mu+, using a sample of 471+/-3 million BBbar events collected with the BaBar detector at the PEP-II e+e- collider at the SLAC National Accelerator Laboratory. We find no evidence for these decays and place 90% confidence level upper limits on their branching fractions Br(B+ -> pi- e+ e+) K- e+ e+) pi- mu+ mu+) K- mu+ mu+) < 6.7 x 10^{-8}.Comment: 8 pages, 4 postscript figures, submitted to Phys. Rev. D. R

    Measurement of Branching Fractions and Rate Asymmetries in the Rare Decays B -> K(*) l+ l-

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    In a sample of 471 million BB events collected with the BABAR detector at the PEP-II e+e- collider we study the rare decays B -> K(*) l+ l-, where l+ l- is either e+e- or mu+mu-. We report results on partial branching fractions and isospin asymmetries in seven bins of di-lepton mass-squared. We further present CP and lepton-flavor asymmetries for di-lepton masses below and above the J/psi resonance. We find no evidence for CP or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.Comment: 16 pages, 14 figures, accepted by Phys. Rev.
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