Capture and Decay of Electroweak WIMPonium

The spectrum of Weakly-Interacting-Massive-Particle (WIMP) dark matter generically possesses bound states when the WIMP mass becomes sufficiently large relative to the mass of the electroweak gauge bosons. The presence of these bound states enhances the annihilation rate via resonances in the Sommerfeld enhancement, but they can also be produced directly with the emission of a low-energy photon. In this work we compute the rate for SU(2) triplet dark matter (the wino) to bind into WIMPonium -- which is possible via single-photon emission for wino masses above 5 TeV for relative velocity v < O(10^{-2}) -- and study the subsequent decays of these bound states. We present results with applications beyond the wino case, e.g. for dark matter inhabiting a nonabelian dark sector; these include analytic capture and transition rates for general dark sectors in the limit of vanishing force carrier mass, efficient numerical routines for calculating positive and negative-energy eigenstates of a Hamiltonian containing interactions with both massive and massless force carriers, and a study of the scaling of bound state formation in the short-range Hulthen potential. In the specific case of the wino, we find that the rate for bound state formation is suppressed relative to direct annihilation, and so provides only a small correction to the overall annihilation rate. The soft photons radiated by the capture process and by bound state transitions could permit measurement of the dark matter's quantum numbers; for wino-like dark matter, such photons are rare, but might be observable by a future ground-based gamma-ray telescope combining large effective area and a low energy threshold.Comment: 3rd version. An interference sign fixed and changes propagated through the paper. Topline qualitative conclusions unchange

Orthopaedic In-Training Examination (OITE) Preparation and Study Habits of Orthopaedic Residents: Revisited

Introduction: The Orthopaedic In-Training Examination (OITE) is well-established as the cornerstone for educational evaluation of orthopaedic surgery residents. Great significance has been placed on the OITE, particularly as it has been found to correlate closely with successful completion of the American Board of Orthopaedic Surgery Part I Exam (ABOS I). Our study correlated different aspects of OITE study preparation, including resources and habits, with OITE performance. Methods: An online survey was created to assess these different aspects and distributed to 163 programs across the United States for distribution to orthopedic residents in each program. Results: Data analysis showed a positive correlation between OITE ranking and greater total hours devoted to studying (r = 0.26, p= 0.0003), earlier start time for exam preparation (r = 0.25, p = 0.0005), orthopaedic journal review (including Journal of Bone and Joint Surgery[r = 0.17, p=0.02] and American Academy of Orthopaedic Surgeons [r = 0.15, p = 0.0475]), review of prior OITE examinations (r = 0.20, p = 0.0054), and use of Orthobullets (r = 0.31, p \u3c 0.0001). 58% of respondents changed their study habits significantly over the course of residency. Most respondents stated they were able to study most effectively on primarily outpatient rotations, as well as pediatrics, sports, and hand orthopaedic rotations. Conclusion: The results of this study may assist residents and residency directors to develop their curriculum and individual study plans to ensure success on the OITE, ABOS I, and, ultimately, their careers as orthopaedic surgeons

Evaluation of hyaluronan content in areas of densification compared to adjacent areas of fascia

Connective tissues between fascia layers are rich in hyaluronan (HA), allowing normal gliding of fascial layers. Fascial densifications contain increased concentration of HA molecules, leading to aggregation of HA chains and altered HA consistency. Restricted fascial gliding, dysfunction and pain may follow. Centers of coordination (CC) are specific points where forces of muscle contraction converge in epimysial fascia to coordinate joint movement. This study compared HA content at a densified CC to adjacent non-densified areas and looked for visible differences between CC and non-CC sites through histological staining techniques

Effect of Monomer Solubility on the Evolution of Copolymer Morphology during Polymerization-Induced Self-Assembly in Aqueous Solution

Polymerization-induced self-assembly (PISA) has become a widely used technique for the rational design of diblock copolymer nano-objects in concentrated aqueous solution. Depending on the specific PISA formulation, reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization typically provides straightforward access to either spheres, worms, or vesicles. In contrast, RAFT aqueous emulsion polymerization formulations often lead to just kinetically-trapped spheres. This limitation is currently not understood, and only a few empirical exceptions have been reported in the literature. In the present work, the effect of monomer solubility on copolymer morphology is explored for an aqueous PISA formulation. Using 2-hydroxybutyl methacrylate (aqueous solubility = 20 g dm–3 at 70 °C) instead of benzyl methacrylate (0.40 g dm–3 at 70 °C) for the core-forming block allows access to an unusual “monkey nut” copolymer morphology over a relatively narrow range of target degrees of polymerization when using a poly(methacrylic acid) RAFT agent at pH 5. These new anisotropic nanoparticles have been characterized by transmission electron microscopy, dynamic light scattering, aqueous electrophoresis, shear-induced polarized light imaging (SIPLI), and small-angle X-ray scattering

PyClaw: Accessible, Extensible, Scalable Tools for Wave Propagation Problems

Development of scientific software involves tradeoffs between ease of use, generality, and performance. We describe the design of a general hyperbolic PDE solver that can be operated with the convenience of MATLAB yet achieves efficiency near that of hand-coded Fortran and scales to the largest supercomputers. This is achieved by using Python for most of the code while employing automatically-wrapped Fortran kernels for computationally intensive routines, and using Python bindings to interface with a parallel computing library and other numerical packages. The software described here is PyClaw, a Python-based structured grid solver for general systems of hyperbolic PDEs \cite{pyclaw}. PyClaw provides a powerful and intuitive interface to the algorithms of the existing Fortran codes Clawpack and SharpClaw, simplifying code development and use while providing massive parallelism and scalable solvers via the PETSc library. The package is further augmented by use of PyWENO for generation of efficient high-order weighted essentially non-oscillatory reconstruction code. The simplicity, capability, and performance of this approach are demonstrated through application to example problems in shallow water flow, compressible flow and elasticity

Resilience in Virginia: Outlook 2021

VCPC\u27s October webinar included an update on Virginia’s participation in the Regional Greenhouse Gas Initiative and the implementation of Executive Order 24; remarks from the Speaker of the House of Delegates, Eileen Filler -Corn, and a legislative panel discussed resilience issues for the upcoming 2021 Virginia General Assembly session. VCPC was honored to host Governor Ralph Northam for Closing Remarks

Resilience in Virginia: Outlook 2021

VCPC\u27s October webinar included an update on Virginia’s participation in the Regional Greenhouse Gas Initiative and the implementation of Executive Order 24; remarks from the Speaker of the House of Delegates, Eileen Filler -Corn, and a legislative panel discussed resilience issues for the upcoming 2021 Virginia General Assembly session. VCPC was honored to host Governor Ralph Northam for Closing Remarks

De Novo Formation of Insulin-Producing “Neo-β Cell Islets” from Intestinal Crypts

SUMMARY The ability to interconvert terminally differentiated cells could serve as a powerful tool for cell-based treatment of degenerative diseases, including diabetes mellitus. To determine which, if any, adult tissues are competent to activate an islet β cell program, we performed an in vivo screen by expressing three β cell “reprogramming factors” in a wide spectrum of tissues. We report that transient intestinal expression of these factors—Pdx1, MafA, and Ngn3 (PMN)—promotes rapid conversion of intestinal crypt cells into endocrine cells, which coalesce into “neoislets” below the crypt base. Neoislet cells express insulin and show ultrastructural features of β cells. Importantly, intestinal neoislets are glucose-responsive and able to ameliorate hyperglycemia in diabetic mice. Moreover, PMN expression in human intestinal “organoids” stimulates the conversion of intestinal epithelial cells into β-like cells. Our results thus demonstrate that the intestine is an accessible and abundant source of functional insulin-producing cells

A multi-level spectral deferred correction method

The spectral deferred correction (SDC) method is an iterative scheme for computing a higher-order collocation solution to an ODE by performing a series of correction sweeps using a low-order timestepping method. This paper examines a variation of SDC for the temporal integration of PDEs called multi-level spectral deferred corrections (MLSDC), where sweeps are performed on a hierarchy of levels and an FAS correction term, as in nonlinear multigrid methods, couples solutions on different levels. Three different strategies to reduce the computational cost of correction sweeps on the coarser levels are examined: reducing the degrees of freedom, reducing the order of the spatial discretization, and reducing the accuracy when solving linear systems arising in implicit temporal integration. Several numerical examples demonstrate the effect of multi-level coarsening on the convergence and cost of SDC integration. In particular, MLSDC can provide significant savings in compute time compared to SDC for a three-dimensional problem