86,661 research outputs found
Chiral symmetry breaking on the lattice: A Study of the strongly coupled lattice Schwinger model
No full textWe reexamine the strong-coupling limit of the Schwinger model on a lattice using staggered fermions and the Hamiltonian approach to lattice gauge theories. Although staggered fermions have no continuous chiral symmetry, they possess a discrete axial invariance that forbids a fermion mass and must be broken in order for the lattice Schwinger model to exhibit the features of the spectrum of the continuum theory. We show that this discrete symmetry is indeed broken spontaneously in the strong-coupling limit. Expanding around a gauge-invariant ground state and carefully considering the normal ordering of the charge operator, we derive an improved strong-coupling expansion and compute the masses of the low-lying bosonic excitations as well as the chiral condensate of the model. We find very good agreement between our lattice calculations and known continuum values for these quantities already in the fourth order of strong-coupling perturbation theory. We also find the exact ground state of the antiferromagnetic Ising spin chain with the long-range Coulomb interaction, which determines the nature of the ground state in the strong-coupling limit
Can a biomimetic osteochondral scaffold be a reliable alternative to prosthetic surgery in treating late-stage SPONK?
No full textBackground: This study aimed to assess the reliability of the Maioregen (R) biomimetic osteochondral scaffold (Finceramica Faenza SpA, Faenza, Italy) as a salvage and joint-preserving procedure in the treatment of late-stage osteonecrosis of the knee.Methods: Eleven active patients aged under 65 years and presenting with clinical and radiological signs of SPONK were treated with Maioregen. All were clinically evaluated pre-operatively and yearly thereafter for a minimum of two years. Subjective IKDC and Lysholm Knee Scale scores were used to assess clinical outcome. A VAS scale served to quantify pre-operative pain and post-operative pain. Activity levels were evaluated pre-operatively and at follow-up using the Tegner Activity Scale.Results: Subjective IKDC (40 +/- 15.0 to 65.7 +/- 14.8 (mean +/- SD)) and Lysholm Knee Scale (49.7 +/- 17.9 to 86.6 +/- 12.7 (mean +/- SD)) scores improved significantly from pre-operative evaluation (p < .01). VAS scores decreased from a pre-operative mean (+/- SD) of 6.3 +/- 2.5 to 1.6 +/- 2.7 at two years. The Tegner Activity Scale showed no significant differences between pre-injury and two-year follow-up.Two out of the 11 patients were symptomatic at 18 months post implant and progressed to condylar collapse. These patients required total knee arthroplasty.Conclusions: Use of a biomimetic scaffold can be a valid option in the surgical treatment of SPONK in relatively young active patients. Indeed, this surgical technique, originally developed for osteochondritis dissecans, has been found to give good clinical results at medium-term follow-up of late-stage osteonecrosis treatment and could postpone or even avoid the need for joint replacement procedures
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Long-term follow-up evaluation of autologous chondrocyte implantation for symptomatic cartilage lesions of the knee: A single-centre prospective study
No full textIntroduction: Autologous Chondrocyte Implantation (ACI) has been the first technique in reconstruction of a valid articular surface. The aim of this study was to evaluate clinical results of this technique at an average follow up of 162 +/- 27 months (range 88-208) in a group of patients who underwent ACI.Materials and methods: 32 patients were operated between 1997 and 2007 for chondral lesions or osteochondritis dissecans of the knee. Mean size of the defect was 5.48 cm(2) +/- 1.53 (range 2-9). Nine patients were treated with I generation technique and 23 with II generation. All patients were evaluated with Subjective IKDC and Tegner Activity Scales for clinical outcomes and with EQ-VAS for a quantitative measure of health after intervention, starting from pre-operative period and at regular follow up (minimum 88 months-maximum 208 months).Results: A significant increment of all scores was noticed comparing preoperative and postoperative results. In particular medium IKDC score increased from 40.3 +/- 9.6 in preoperative evaluation to 74.2 +/- 11.6 at one year (p < 0.00001) and to 83.9 +/- 10.4 at 5 years follow up (p < 0.001). Mean IKDC values at the last follow-up were 80.3 +/- 14.2, showing no statistical differences with those obtained at five-year follow-up. Tegner Activity Scale values increased from 2.8 +/- 1.1 preoperatively to 4.1 +/- 1.1 (p < 0.0001) after one year and to 6 +/- 1.1 at five years (p < 0.0001). Mean Tegner Activity Scale values decreased to 4.8 +/- 1.4 at the last follow-up. EQ-VAS evaluation showed superposable results comparing the 5 years evaluation with the ones at a medium follow up of 162 +/- 27 months.Discussion: The most important finding is the reliability at long-term of ACI technique, which in our series gave excellent clinical results. No statistical differences were observed between first-and secondgeneration. Clinical outcomes were significantly better for defects in the femoral condyles, influenced by age (worse results over 30 years old).Conclusions: ACI represents a valid technique for chondral and osteochondral lesions of the knee in a population heterogeneous for age, sex and activity level with good results even at a long term follow up
Patellofemoral instability: classification and imaging
No full textPatellofemoral disorders must be approached through an appropriate process of diagnostic framing, performed using language that is, as far as possible, unequivocal and a validated and organic classification system. At present, the classification proposed by the Lyonnaise school, which fulfills these requirements, is the most complete. This classification divides patellofemoral disorders into three groups: objective patellar instability, potential patellar instability and painful patella syndrome. It also identifies three principal factors of instability: trochlear dysplasia, abnormal patellar height and pathological tibial tubercle-trochlear groove (TT-TG) distance. Imaging is crucial for correct classification and for identifying and measuring the principal factors of instability. Up to now, the emphasis has been placed on the contribution made by traditional diagnostic radiology and computed tomography. In recent years, however, growing attention has been paid to the use of magnetic resonance imaging in the assessment of the patellofemoral joint and in the study of factors of instability, even though there is still a need for validation of this approach before it can be routinely used in preoperative planning
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
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