Search

Purpose: To determine the likelihood of and risk factors for tear progression among patients with a symptomatic partial or full-thickness rotator cuff tears (RCTs) who return with continued shoulder pain and obtain subsequent magnetic resonance imaging (MRI) and to identify various patient factors and MRI findings associated with rotator cuff tear progression. Methods: We performed a retrospective review of MRI studies from Veteran’s Affair patients with conservatively treated partial- or full-thickness rotator cuff tears. Patient characteristics and demographics were obtained via chart review. Tear characteristics were measured on MRI obtained a minimum of 1 year apart. We defined progression as either (1) an increase from a partial to a full-thickness tear or (2) an increase in tear width or retraction of at least 5 mm. Statistical analysis using χ2, Fisher exact, Student t, and Mann–Whitney U test was then performed as appropriate, looking for factors involved in RCT progression. Results: We evaluated 412 MRI studies from 206 Veteran’s Affair patients with conservatively treated partial- or full-thickness rotator cuff tears from October 1999 to March 2020. Overall, 61% of RCTs had progressed at a mean of 3.2 ± 2.3 years follow-up. Among all patients, 74% of full-thickness tears progressed in size, 42% of partial-thickness tears progressed in size, and 29% of partial-thickness tears progressed to full-thickness tears. On univariate analysis, full-thickness tears (P < .001), disruption of the anterior rotator cuff cable (P = .001), subscapularis involvement (P = .004), tear retraction (P < .001), and tear width (P < .001) all increased the likelihood of progression. On multivariate analysis, full-thickness tears (P < .001) and subscapularis involvement (P = .045) were correlated with progression. Conclusions: RCTs progress over time in terms of size of tear and from partial- to full-thickness tears. There is an increased risk of tear progression in patients with full-thickness tears when compared with partial-thickness tears along with subscapularis tear involvement. Rates of progression are larger than previously reported rates for both partial- and full-thickness tears, noting that our study population were those patients who continued to be symptomatic from their tears. Level of Evidence: Level IV, prognostic case series.

Large bore (Case II) quadrupole focusing magnets for the Advanced Hydrotest Faciliity (AHF) at Los Alamos, NM, are described and discussed.

The Levitated Dipole Experiment approach to magnetic confinement of fusion plasma is examined in terms of design, fabrication and test of react and wind, NB3Sn.

A study was conducted on the prototype joint sample which was designed and fabricated by the US-party for the International Thermonuclear Experimental Reactor. Requirements for the full-size joint involve the capacity to operate under alternating current background fields at minimal coupling losses. An overview of the design and fabrication effort, with particular emphasis on procedural steps, is presented.

The magnet system for the Superconducting Super Collider (SSC) Gamma, Electrons and Muons (GEM) detector consists of a single layer, superconducting, split solenoid and two iron forward field shapers (FFS). In addition, major structura components, such as the central detector and FFS support structures and the vacuum vessels, are to be built with magnetic steel. This paper presents the nonlinear, two and three-dimensional electromagnetic analyses which are performed in support of the overall design effort. A detailed axisymmetric, finite element ANSYS model is used to determine the magnetic field distribution in the region of the detector, and the electromagnetic forces acting on the coi and various magnetic steel elements. A 3-D model is developed to capture the magnetic field perturbations produced by asymmetric, magnetic structural elements. The model produces 3-D field maps of the detector volume to evaluate the effects of these asymmetries on the detector resolution. Another 3-D model is used to determine the distribution of magnetic steel plates required to shield the nearby Electronic Rack Room from the coil's fringe field.

The GEM Detector magnet at the Superconducting Super Collider is built in two halves each of which is comprised of 12 single layer superconducting coil modules wound on a 19 m mean diameter and joined with a low resistance lap joint employing the superconducting strands and a copper stabilizer. Each joint half is attached to the sheathed, cable-in-conduit conductor end, and assembly of the mating halves is completed in the field. The target resistance per joint is 5 X [10.sup.-10] [Omega] at an operating current of 50 kA. Details of the joint design, its cooling and results of tests on prototypical sub- and full-scale models using superconducting strands are presented.

Background: Pose estimation (PE) has the promise to measure pediatric movement from a video recording. The purpose of this study was to quantify the accuracy of a PE model to detect arm and leg movements in 3-month-old infants with and without (TD, for typical development) complex congenital heart disease (CCHD). Methods: Data from 12 3-month-old infants (N = 6 TD and N = 6 CCHD) were used to assess MediaPipe's full-body model. Positive predictive value (PPV) and sensitivity assessed the model's accuracy with behavioral coding. Results: Overall, 499 leg and arm movements were identified, and the model had a PPV of 85% and a sensitivity of 94%. The model's PPV in TD was 84% and the sensitivity was 93%. The model's PPV in CCHD was 87% and the sensitivity was 98%. Movements per hour ranged from 399 to 4211 for legs and 236 to 3767 for arms for all participants, similar ranges to the literature on wearables. No group differences were detected. Conclusions: There is a strong promise for PE and models to describe infant movements with accessible and affordable resources—like a cell phone and curated video repositories. These models can be used to further improve developmental assessments of limb function, movement, and changes over time. [ABSTRACT FROM AUTHOR]

Ligaments and tendons serve a variety of important functions in maintaining the structure of the human body. Although abundant literature exists describing experimental investigations of these tissues, mathematical modeling of ligaments and tendons also contributes significantly to understanding their behavior. This paper presents a survey of developments in mathematical modeling of ligaments and tendons over the past 20 years. Mathematical descriptions of ligaments and tendons are identified as either elastic or viscoelastic, and are discussed in chronological order. Elastic models assume that ligaments and tendons do not display time dependent behavior and thus, they focus on describing the nonlinear aspects of their mechanical response. On the other hand, viscoelastic models incorporate time dependent effects into their mathematical description. In particular, two viscoelastic models are discussed in detail; quasi-linear viscoelasticity (QLV), which has been widely used in the past 20 years, and the recently proposed single integral finite strain (SIFS) model.

The development of a cable-in-conduit superconductor for the Superconducting Super Collider Laboratory's GEM Detector Magnet is reported. The conductor, which is composed of a 450-strand niobium titanium cable jacketed by an aluminum-sheathed stainless steel conduit. Its design is based on the specifications for the detector magnet which includes two superconducting 19-m by 14-m coils and stable dc operation.

The Gammas, Electrons and Muons detector magnet is a key component of the Superconducting Super Collider accelerator. Its features include a solenoid coil made of aluminum-sheathed cable-in-conduit conductors for an operating current of 50 kA. Designed for on-site winding and assembly, it provides a magnetic field of 0.8 T and stores 2.5 GJ of energy. The magnet also employs a natural thermosiphon loop for cooling by thermal radiation.