Eruption of magnetic flux ropes during flux emergence

Aims: We investigate the formation of flux ropes in a flux emergence region and their rise into the outer atmosphere of the Sun. Methods: We perform 3D numerical experiments solving the time-dependent and resistive MHD equations. Results: A sub-photospheric twisted flux tube rises from the solar interior and expands into the corona. A flux rope is formed within the expanding field, due to shearing and reconnection of field lines at low atmospheric heights. If the tube emerges into a non-magnetized atmosphere, the flux rope rises, but remains confined inside the expanding magnetized volume. On the contrary, if the expanding tube is allowed to reconnect with a preexisting coronal field, the flux rope experiences a full eruption with a rise profile which is in qualitative agreement with erupting filaments and Coronal Mass Ejections

Modeling the Impacts of Sea Level Rise in Coastal Virginia at Multiple Scales

Relative sea level is increasing along the Mid-Atlantic coast of the United States and the rate of relative sea level rise (ΔRSL) for Coastal Virginia is approximately double the rate of global sea level rise (ΔSLRG)(1). The potential impacts posed to communities by ΔRSL are best understood by examining the spatial relationship between the upper limits of ocean-connected waters and the geographic positioning of critical natural and societal assets. This research examines this problem at three spatial scales to quantify the impacts of ΔRSL and storm flooding events on (i) structural and transportation infrastructure for the tide-influenced coastal zone of Virginia, (ii) physical and socioeconomic assets in Hampton Roads, and (iii) critical infrastructure at Port of Virginia’s Norfolk International Terminal South (NITS). Spatial modeling of future sea level rise produced data and maps of potential inundation and provided an assessment of impacts to land areas, roadways, and buildings throughout coastal Virginia. The total land area predicted to be inundated by sea level rise was 424 square miles (682 km2) in 2040, 534 square miles (859 km2) in 2060, and 649 square miles (1044 km2) in 2080. Modeling of a Category 1 hurricane (like Florence in 2018) making landfall near Virginia Beach and travelling westward through Hampton Roads with future ΔRSL of +1.5 feet (.46 m) and +3 feet (.91 m) predicted significant flooding and physical damages, including impairment to critical emergency services such as police, fire, and emergency medical transport. Modeling of hurricane storm surge with future ΔRSL to predict potential flooding at Port of Virginia’s NITS facility proved to be an effective screening tool for estimating current and future risk to critical facilities. Modeling revealed a near-linear pattern of vulnerability wherein the surface area predicted to be inundated by storms of identical category progressively increased as sea level increased. The multi-scale, -source, and -temporal techniques developed in this inundation modeling research provide data and replicable methodologies that others may use as a proven platform to calculate potential losses of natural resource, property, economy, and life resulting from inundation resulting from ΔRSL

The Utility of Preoperative Inflammatory Marker Collection in Avoiding Unnecessary Postoperative Infection Workup

BACKGROUND: Increased surgical volume has resulted in higher levels of postoperative TKA periprosthetic joint infection (PJI) which can cause implant failure, systemic infection, and possible amputation. While postoperatively elevated levels of inflammatory markers, such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), can be indicative of periprosthetic joint infection, these laboratory tests can have inconsistent specificities and sensitivities which can ultimately result in increased healthcare costs and postoperative complications. OBJECTIVES: The objective of this study is to provide evidence for the utility of collecting preoperative patient erythrocyte sedimentation rate and c-reactive protein laboratory values. METHODS: This retrospective study included 337 patients who underwent total knee arthroplasty (TKA) from 2016 through 2022. Patients who underwent contralateral TKA were excluded from this analysis to avoid overlap with routine preoperative TKA laboratory collection for the second TKA. Pre- and postoperative (within 6 months) erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in patients who underwent TKA were analyzed. Elevated ESR and CRP values were defined using criteria as being above 36 mm/hr and 8.2 mg/L, respectively. RESULTS: Patients were predominantly females (68%) with a racial majority of Caucasians (58%) followed by Black/African American patients (36%). Prior to surgery, 20% of the patients had elevated CRP and 25% had elevated ESR. Within 6 months postoperative, labs were ordered on 41 and 36 patients for CRP and ESR, respectively. Twenty-three patients (56%, 23/41) had elevated CRP values, of which 5 (22%, 5/23) had elevated CRP values prior to surgery with the remaining 18 (78%, 18/23) within normal ranges preoperatively. Twenty-one patients (58%, 21/36) had postoperatively elevated ESR, of which 8 (38%, 8/21) had elevated ESR values prior to surgery with the remaining 13 (62%, 13/21) within normal ranges preoperatively. CONCLUSIONS: Approximately one third of the patients with elevated postoperative labs also had elevated labs prior to surgery, indicating that risk factors other than periprosthetic joint infection might be the cause. By establishing baseline inflammatory marker values of these patients, it is possible to reduce risks of unnecessary infection workup and decrease healthcare costs

Analytical, Optimal, and Sparse Optimal Control of Traveling Wave Solutions to Reaction-Diffusion Systems

This work deals with the position control of selected patterns in reaction-diffusion systems. Exemplarily, the Schl\"{o}gl and FitzHugh-Nagumo model are discussed using three different approaches. First, an analytical solution is proposed. Second, the standard optimal control procedure is applied. The third approach extends standard optimal control to so-called sparse optimal control that results in very localized control signals and allows the analysis of second order optimality conditions.Comment: 22 pages, 3 figures, 2 table

STM and RHEED study of the Si(001)-c(8x8) surface

The Si(001) surface deoxidized by short annealing at T~925C in the ultrahigh vacuum molecular beam epitaxy chamber has been in situ investigated by high resolution scanning tunnelling microscopy (STM) and reflected high energy electron diffraction (RHEED). RHEED patterns corresponding to (2x1) and (4x4) structures were observed during sample treatment. The (4x4) reconstruction arose at T<600C after annealing. The reconstruction was observed to be reversible: the (4x4) structure turned into the (2x1) one at T>600C, the (4x4) structure appeared again at recurring cooling. The c(8x8) reconstruction was revealed by STM at room temperature on the same samples. A fraction of the surface area covered by the c(8x8) structure decreased as the sample cooling rate was reduced. The (2x1) structure was observed on the surface free of the c(8x8) one. The c(8x8) structure has been evidenced to manifest itself as the (4x4) one in the RHEED patterns. A model of the c(8x8) structure formation has been built on the basis of the STM data. Origin of the high-order structure on the Si(001) surface and its connection with the epinucleation phenomenon are discussed.Comment: 26 pages, 12 figure

Branch Mode Selection during Early Lung Development

Many organs of higher organisms, such as the vascular system, lung, kidney, pancreas, liver and glands, are heavily branched structures. The branching process during lung development has been studied in great detail and is remarkably stereotyped. The branched tree is generated by the sequential, non-random use of three geometrically simple modes of branching (domain branching, planar and orthogonal bifurcation). While many regulatory components and local interactions have been defined an integrated understanding of the regulatory network that controls the branching process is lacking. We have developed a deterministic, spatio-temporal differential-equation based model of the core signaling network that governs lung branching morphogenesis. The model focuses on the two key signaling factors that have been identified in experiments, fibroblast growth factor (FGF10) and sonic hedgehog (SHH) as well as the SHH receptor patched (Ptc). We show that the reported biochemical interactions give rise to a Schnakenberg-type Turing patterning mechanisms that allows us to reproduce experimental observations in wildtype and mutant mice. The kinetic parameters as well as the domain shape are based on experimental data where available. The developed model is robust to small absolute and large relative changes in the parameter values. At the same time there is a strong regulatory potential in that the switching between branching modes can be achieved by targeted changes in the parameter values. We note that the sequence of different branching events may also be the result of different growth speeds: fast growth triggers lateral branching while slow growth favours bifurcations in our model. We conclude that the FGF10-SHH-Ptc1 module is sufficient to generate pattern that correspond to the observed branching modesComment: Initially published at PLoS Comput Bio