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The most effective way to achieve very high collision energies in a circular particle accelerator is to maximize the field strength of the main bending dipoles. In dipole magnets using Nb-Ti superconductor the practical field limit is considered to be 8-9 T. When Nb3Sn superconductor material is utilized, a field level of 15-16 T can be achieved. To further push the magnetic field beyond the Nb3Sn limits, High Temperature Superconductors (HTS) need to be considered in the magnet design. The most promising HTS materials for particle accelerator magnets are Bi2212 and REBCO. However, their outstanding performance comes with a significantly higher cost. Therefore, an economically viable option towards 20 T dipole magnets could consist in an 'hybrid' solution, where both HTS and Nb3Sn materials are used. We discuss in this paper preliminary conceptual designs of various 20 T hybrid magnet concepts. After the definition of the overall design criteria, the coil dimensions and parameters are investigated with finite element models based on simple sector coils. Preliminary 2D cross-section computation results are then presented and three main layouts compared: cos-theta, block, and common-coil. Both traditional designs and more advanced stress-management options are considered.

The U.S. Magnet Development Program (MDP) collaboration is designing a utility mechanical structure for testing various high-field superconducting dipole coils. The design uses a shell-based structure concept, which allows applying preload in two steps: During a room temperature assembly and during a cool down to a cryogenic temperature. The structure is designed to accommodate various coil designs - including Nb3Sn Cosine Theta (CT) and Canted CT magnets as well as hybrid magnets with high temperature superconductor cables. Superconducting coils, enclosed by bolted pads to form an octagonal coil pack, will be inserted into a reusable yoke-shell subassembly and precisely preloaded during the assembly using a bladder-and-key technology. Due to a differential thermal contraction between an external aluminum shell and the magnet core, the coil preload increases during the cool down up to level required for 17-T excitation. Such a reusable structure will serve as a testing fixture supporting goals of the MDP program, decreasing cost and simplifying coil performance testing at different preload levels. We present a finite-element analysis of the structure preloading various coil designs and examine the predicted coil stress at each step of the magnet assembly and excitation.

A future circular collider (FCC) with a center-of-mass energy of 100 TeV and a circumference of around 100 km, or an energy upgrade of the LHC (HE-LHC) to 27 TeV require bending magnets providing 16 T in a 50-mm aperture. Several development programs for these magnets, based on Nb3Sn technology, are being pursued in Europe and in the U.S. In these programs, cos-theta, block-type, common-coil, and canted-cos-theta magnets are explored; first model magnets are under manufacture; limits on conductor stress levels are studied; and a conductor with enhanced characteristics is developed. This paper summarizes and discusses the status, plans, and preliminary results of these programs.

A next step of energy increase of hadron colliders beyond the LHC requires high-field superconducting magnets capable of providing a dipolar field in the range of 16 T in a 50-mm aperture with accelerator quality. These characteristics could meet the requirements for an upgrade of the LHC to twice the present beam energy or for a 100-TeV center of mass energy future circular collider. This paper summarizes the activities and plans for the development of these magnets, in particular within the 16 T Magnet Technology Program, the WP5 of the EuroCirCol, and the U.S. Magnet Development Program.

Background: Minimally-invasive endoscopic strip-craniectomy (or suturectomy) for the repair of craniosynostosis combined with postoperative cranial orthotic molding has been widely adopted in the past 2 decades, proving itself as a safe and effective procedure. Over time the authors transitioned from performing an endoscopic strip-craniectomy, to performing the same surgery without the endoscope. The authors here describe our technique and compare its results to those published in the literature for endoscopic suturectomies., Methods: A retrospective chart review was performed for patients with nonsyndromic craniosynostosis who underwent minimally-invasive nonendoscopic suturectomy between 2019 and 2020 at our institution., Results: Thirteen patients (11 males; 2 females) were operated including 5 Metopic, 5 Sagittal, 2 coronal, and 1 lambdoid craniosynostosis. The average age at surgery was 4.35 months. The average length of surgery was 71 minutes. Averaged intraoperative estimated blood loss was 31.54 mL. Eleven patients received a blood transfusion (most before performing the skin incision) with a mean amount of 94.62 mL of blood transfused during surgery. The mean hemoglobin at discharge was 10.38 mg/dL. There was only 1 intraoperative mild complication. The mean intrahospital length of stay was 1.77 days with no postoperative complications noted. All patients initiated remodeling orthotic treatment following surgery. Long-term follow-up scans were available for 8 patients (5 metopic, 2 sagittal, and 1 lambdoid) with an average follow-up of 9 months. In all cases, there was a significant improvement in the skull width at the synostosis location as well as in the skull proportions and symmetry. The above outcomes are similar to those published in the literature for endoscope-assisted strip-craniectomies., Conclusions: Suturectomies assisted with cranial orthosis remodeling for the treatment of all types of nonsyndromic craniosynostosis can be performed without an endoscope while maintaining minimal-invasiveness, good surgical results, and low complication rates., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Background: Diabetic patients have an increased predisposition to thromboembolic events, in most cases originating from thrombi in the left atrial appendage (LAA). Remodeling of the LAA, which predisposes to thrombi formation, has been previously described in diabetic patients with atrial fibrillation, but whether remodeling of the LAA occurs in diabetics also in the absence of atrial fibrillation is unknown. To investigate the contribution of diabetes, as opposed to atrial fibrillation, to remodeling of the LAA, we went from humans to the animal model., Methods: We studied by echocardiography the structure and function of the heart over multiple time points during the evolution of diabetes in the Cohen diabetic sensitive rat (CDs/y) provided diabetogenic diet over a period of 4 months; CDs/y provided regular diet and the Cohen diabetic resistant (CDr/y), which do not develop diabetes, served as controls. All animals were in sinus rhythm throughout the study period., Results: Compared to controls, CDs/y developed during the evolution of diabetes a greater heart mass, larger left atrial diameter, wider LAA orifice, increased LAA depth, greater end-diastolic and end-systolic diameter, and lower E/A ratio-all indicative of remodeling of the LAA and left atrium (LA), as well as the development of left ventricular diastolic dysfunction. To investigate the pathophysiology involved, we studied the histology of the hearts at the end of the study. We found in diabetic CDs/y, but not in any of the other groups, abundance of glycogen granules in the atrial appendages , atria  and ventricles, which may be of significance as glycogen granules have previously been associated with cell and organ dysfunction in the diabetic heart., Conclusions: We conclude that our rodent model of diabetes, which was in sinus rhythm, reproduced structural and functional alterations previously observed in hearts of human diabetics with atrial fibrillation. Remodeling of the LAA and of the LA in our model was unrelated to atrial fibrillation and associated with accumulation of glycogen granules. We suggest that myocardial accumulation of glycogen granules is related to the development of diabetes and may play a pathophysiological role in remodeling of the LAA and LA, which predisposes to atrial fibrillation, thromboembolic events and left ventricular diastolic dysfunction in the diabetic heart., (© 2021. The Author(s).)