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result(s) for
"Weisberg, D"
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A high-density and high-confinement tokamak plasma regime for fusion energy
by
Qian, J. P.
,
Holcomb, C. T.
,
Hyatt, A. W.
in
639/4077/4091/4093
,
639/766/1960/1136
,
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
2024
The tokamak approach, utilizing a toroidal magnetic field configuration to confine a hot plasma, is one of the most promising designs for developing reactors that can exploit nuclear fusion to generate electrical energy
1
,
2
. To reach the goal of an economical reactor, most tokamak reactor designs
3
–
10
simultaneously require reaching a plasma line-averaged density above an empirical limit—the so-called Greenwald density
11
—and attaining an energy confinement quality better than the standard high-confinement mode
12
,
13
. However, such an operating regime has never been verified in experiments. In addition, a long-standing challenge in the high-confinement mode has been the compatibility between a high-performance core and avoiding large, transient edge perturbations that can cause very high heat loads on the plasma-facing-components in tokamaks. Here we report the demonstration of stable tokamak plasmas with a line-averaged density approximately 20% above the Greenwald density and an energy confinement quality of approximately 50% better than the standard high-confinement mode, which was realized by taking advantage of the enhanced suppression of turbulent transport granted by high density-gradients in the high-poloidal-beta scenario
14
,
15
. Furthermore, our experimental results show an integration of very low edge transient perturbations with the high normalized density and confinement core. The operating regime we report supports some critical requirements in many fusion reactor designs all over the world and opens a potential avenue to an operating point for producing economically attractive fusion energy.
A stable tokamak plasma has been demonstrated with a high plasma density and a high energy confinement quality, both of which are simultaneously important for fusion reactors.
Journal Article
Integration of full divertor detachment with improved core confinement for tokamak fusion plasmas
2021
Divertor detachment offers a promising solution to the challenge of plasma-wall interactions for steady-state operation of fusion reactors. Here, we demonstrate the excellent compatibility of actively controlled full divertor detachment with a high-performance (
β
N
~ 3,
H
98
~ 1.5) core plasma, using high-β
p
(poloidal beta,
β
p
> 2) scenario characterized by a sustained core internal transport barrier (ITB) and a modest edge transport barrier (ETB) in DIII-D tokamak. The high-
β
p
high-confinement scenario facilitates divertor detachment which, in turn, promotes the development of an even stronger ITB at large radius with a weaker ETB. This self-organized synergy between ITB and ETB, leads to a net gain in energy confinement, in contrast to the net confinement loss caused by divertor detachment in standard H-modes. These results show the potential of integrating excellent core plasma performance with an efficient divertor solution, an essential step towards steady-state operation of reactor-grade plasmas.
Plasma fusion devices like tokamaks are important for energy generation but there are many challenges for their steady state operation. Here, the authors show that full divertor detachment is compatible with high-confinement high-poloidal-beta core plasmas and this prevents the damage to the divertor target plates and the first wall.
Journal Article
Differential Spatiotemporal Expression of Type I and Type II Cadherins Associated With the Segmentation of the Central Nervous System and Formation of Brain Nuclei in the Developing Mouse
2021
Type I and type II classical cadherins comprise a family of cell adhesion molecules that regulate cell sorting and tissue separation by forming specific homo and heterophilic bonds. Factors that affect cadherin-mediated cell-cell adhesion include cadherin binding affinity and expression level. This study examines the expression pattern of type I cadherins ( Cdh1 , Cdh2 , Cdh3 , and Cdh4 ), type II cadherins ( Cdh6 , Cdh7 , Cdh8 , Cdh9 , Cdh10 , Cdh11 , Cdh12 , Cdh18 , Cdh20 , and Cdh24 ), and the atypical cadherin 13 ( Cdh13 ) during distinct morphogenetic events in the developing mouse central nervous system from embryonic day 11.5 to postnatal day 56. Cadherin mRNA expression levels obtained from in situ hybridization experiments carried out at the Allen Institute for Brain Science ( https://alleninstitute.org/ ) were retrieved from the Allen Developing Mouse Brain Atlas. Cdh2 is the most abundantly expressed type I cadherin throughout development, while Cdh1 , Cdh3 , and Cdh4 are expressed at low levels. Type II cadherins show a dynamic pattern of expression that varies between neuroanatomical structures and developmental ages. Atypical Cdh13 expression pattern correlates with Cdh2 in abundancy and localization. Analyses of cadherin-mediated relative adhesion estimated from their expression level and binding affinity show substantial differences in adhesive properties between regions of the neural tube associated with the segmentation along the anterior–posterior axis. Differences in relative adhesion were also observed between brain nuclei in the developing subpallium (basal ganglia), suggesting that differential cell adhesion contributes to the segregation of neuronal pools. In the adult cerebral cortex, type II cadherins Cdh6 , Cdh8 , Cdh10 , and Cdh12 are abundant in intermediate layers, while Cdh11 shows a gradated expression from the deeper layer 6 to the superficial layer 1, and Cdh9 , Cdh18 , and Cdh24 are more abundant in the deeper layers. Person’s correlation analyses of cadherins mRNA expression patterns between areas and layers of the cerebral cortex and the nuclei of the subpallium show significant correlations between certain cortical areas and the basal ganglia. The study shows that differential cadherin expression and cadherin-mediated adhesion are associated with a wide range of morphogenetic events in the developing central nervous system including the organization of neurons into layers, the segregation of neurons into nuclei, and the formation of neuronal circuits.
Journal Article
Complications and Readmissions After Total Hip Replacement in Octogenarians and Nonagenarians
by
Saleh, Ahmed
,
Erez, Orry
,
Yohe, Nicholas
in
Hip joint
,
Joint replacement surgery
,
Oldest old people
2020
Introduction:
As the US population ages, the need for total hip arthroplasty (THA) is predicted to increase by 174% by 2030. The purpose of our study was to examine the rate and risks of 30-day complications and unplanned readmission in patients over the age of 80 years old.
Materials and Methods:
The National Surgical Quality Improvement Project database for the years 2008 to 2014 was queried for patients over the age of 80 undergoing THA. The risks of major complications, minor complications, bleeding occurrences, unplanned readmissions, and deaths over a 30-day period were examined using univariate and multivariate analyses.
Results:
A total of 7730 patients were included for analysis; 324 (4.2%) patients experienced a major complication, 1944 (25.1%) patients experienced a minor complication, 1776 (22.9%) patients had a bleeding occurrence requiring transfusion, and 376 (4.9%) patients experienced an unplanned readmission to the hospital within 30 days. A total of 33 (0.4%) patient deaths were recorded within 30 days postoperatively. Patients with congestive heart failure were at increased risk for developing a major complication, odds ratio (OR) 3.618 (1.052-12.437), and postoperative death, OR 11.920 (1.362-104.322). Patients with an American Society of Anesthesiologists >2, OR: 1.351 (1.131-1.613), and an operative time greater than 120 minutes, OR: 1.346 (1.084-1.670), had increased risks of minor complications. Patients with a body mass index greater than 30 had reduced rates of minor complications, OR: 0.609 (0.486-0.763). Increased risk of unplanned readmission was seen in patients with chronic obstructive pulmonary disease, OR: 2.403 (1.324-4.359).
Discussion/Conclusion:
Elderly patients undergoing THA have high complication and readmission rates. Surgeons should convey these increased risk factors and rates of complications in elective THAs to their elderly patients and work with primary care physicians to mitigate these risks.
Journal Article
The Wisconsin Plasma Astrophysics Laboratory
by
Egedal, J.
,
Clark, M.
,
Siller, R.
in
Astrophysics
,
Cobalt
,
Experiments at the Frontier of Fundamental Plasma Physics
2015
The Wisconsin Plasma Astrophysics Laboratory (WiPAL) is a flexible user facility designed to study a range of astrophysically relevant plasma processes as well as novel geometries that mimic astrophysical systems. A multi-cusp magnetic bucket constructed from strong samarium cobalt permanent magnets now confines a
$10~\\text{m}^{3}$
, fully ionized, magnetic-field-free plasma in a spherical geometry. Plasma parameters of
$T_{e}\\approx 5$
to
$20~\\text{eV}$
and
$n_{e}\\approx 10^{11}$
to
$5\\times 10^{12}~\\text{cm}^{-3}$
provide an ideal testbed for a range of astrophysical experiments, including self-exciting dynamos, collisionless magnetic reconnection, jet stability, stellar winds and more. This article describes the capabilities of WiPAL, along with several experiments, in both operating and planning stages, that illustrate the range of possibilities for future users.
Journal Article
Comparison of baseline demographics and risk factors for aseptic loosening following primary total elbow arthroplasty
2023
BackgroundAseptic loosening is a feared complication following total elbow arthroplasty (TEA); however, literature regarding factors that may contribute to this complication is limited. The aims of this investigation were to: (1) compare baseline demographics of patients who developed aseptic loosening following primary TEA; and (2) identify patient-specific risk factors for the development of loosening.MethodsRetrospective analysis using a nationwide claims database was performed to identify patients who underwent primary TEA and developed aseptic loosening within 2 years (study n = 307, control n = 10,741). Multivariate regression analysis generated odds ratio (OR), 95% confidence interval (95% CI), and p-value of risk factors. p < 0.05 was considered statistically significant.ResultsPatients who developed aseptic loosening had significant differences in numerous demographics, including age (p = 0.0001), sex (p = 0.0251), and various comorbid conditions such as obesity (15.96% vs. 8.36%, p < 0.0001). Furthermore, the risk factors most associated with aseptic loosening were obesity (OR 1.65, 95% CI 1.18–2.28, p = 0.002), male sex (OR 1.51, 95% CI 1.13–2.00, p = 0.004), and concomitant opioid use disorder (OR 1.58, 95% CI 1.14–2.15, p = 0.004).DiscussionThis study is the first to identify demographics and patient-related risk factors associated with aseptic loosening following primary TEA. This evidence could be applied to the clinical setting in order to educate at-risk patients of this potential complication as well as inform their post-operative clinical management.Level of evidenceLevel III: Prognostic
Journal Article
The influence of prior dental pathology on medical complications and peri-prosthetic joint infections following primary shoulder arthroplasty
by
Gordon, Adam M
,
Sadeghpour, Ramin
,
Diamond, Keith B
in
Antibiotics
,
Dental implants
,
Expenditures
2023
PurposeAntibiotic prophylaxis before invasive dental procedures is a common practice in the USA. Consensus regarding the influence of prior dental pathology (DP) on postoperative complications is lacking. The objectives are to determine the association of DP prior to shoulder arthroplasty (SA) on: (1) lengths of stay (LOS), (2) medical complications, (3) readmissions, (4) implant-related complications including peri-prosthetic joint infections (PJIs) and (5) healthcare expenditures.MethodsThe PearlDiver database was queried for primary shoulder arthroplasty from 2010 to 2020. Patients with history of dental caries or dental implant placement before SA represented the study group (n = 1419). Patients without prior DP represented controls (n = 7062). Study group patients were 1:5 ratio matched to controls by age, sex, and comorbidities. Outcomes included LOS, 90-day complications, readmissions, 2-year implant-related complications, and healthcare reimbursements. Logistic regression was used to calculate odds ratios (OR) of complications and readmissions. T tests compared LOS and costs. P values < 0.003 were significant.ResultsLOS (2.17 vs. 2.07 days; p = 0.071) were similar between groups. Patients with DP had higher 90-day medical complications compared to controls (OR: 1.74, p < 0.0001), including myocardial infarctions (2.2% vs. 0.8%; OR: 2.79, p < 0.0001), acute kidney injuries (8.3% vs. 4.6%; OR: 1.92, p < 0.0001), and pneumonias (8.7% vs. 5.3%; OR: 1.72, p < 0.0001). Readmission rates (1.97% vs. 1.54%; p = 0.248) were similar. Two-year implant complications were higher in patients with DP compared to controls (16.1% vs. 11.5%; OR: 1.38, p = 0.0003), including dislocations (6.4% vs. 4.5%; OR: 1.45, p = 0.002) and mechanical loosenings (4.0% vs. 2.4%; OR: 1.67, p = 0.001); however, PJIs were similar (2.2% vs. 1.9%; OR: 1.12, p = 0.583). Healthcare expenditures between groups were similar ($12,611 vs. $12,059; p = 0.075).ConclusionPatients with prior DP have higher 90-day medical complications and 2-year implant-related complications. Two-year incidence of PJIs were similar between groups. These findings can help shoulder surgeons counsel patients with a pertinent dental history.Level of evidence III. Retrospective comparative study.
Journal Article
COVID-19 Peripheral Neuropathy: A Report of Three Cases
by
Erez, Orry
,
Diamond, Keith B
,
Edelstein, David
in
Epidemiology/Public Health
,
Neurology
,
Orthopedics
2021
This study includes three patients with various peripheral neuropathies after contracting coronavirus disease 2019 (COVID-19) infection, treated both conservatively and surgically. While cases of neurological complications have been described, neuropathy associated with COVID-19 is under-reported in orthopaedic literature. These patients presented with ulnar neuropathy, critical care polyneuropathy (CCP) with anterior interosseous nerve (AIN) neuropathy, and lateral femoral cutaneous nerve (LFCN) neuropathy. COVID-19 infection may be associated with peripheral neuropathy in addition to various neurological sequelae. Orthopaedic surgeons should screen patients for recent infections and evaluate the severity of the illness to assess for risk of neurological sequelae of COVID-19 infection.This study includes three patients with various peripheral neuropathies after contracting coronavirus disease 2019 (COVID-19) infection, treated both conservatively and surgically. While cases of neurological complications have been described, neuropathy associated with COVID-19 is under-reported in orthopaedic literature. These patients presented with ulnar neuropathy, critical care polyneuropathy (CCP) with anterior interosseous nerve (AIN) neuropathy, and lateral femoral cutaneous nerve (LFCN) neuropathy. COVID-19 infection may be associated with peripheral neuropathy in addition to various neurological sequelae. Orthopaedic surgeons should screen patients for recent infections and evaluate the severity of the illness to assess for risk of neurological sequelae of COVID-19 infection.
Journal Article
Exploring the fusion power plant design space: comparative analysis of positive and negative triangularity tokamaks through optimization
2026
The optimal configuration choice between positive triangularity (PT) and negative triangularity (NT) tokamaks for fusion power plants hinges on navigating different operational constraints rather than achieving specific plasma performance metrics. This study presents a systematic comparison using constrained multi-objective optimization with the integrated FUsion Synthesis Engine (FUSE) framework. Over 200,000 integrated design evaluations were performed exploring the trade-offs between capital cost minimization and operational reliability (maximizing \\(q_{95}\\)) while satisfying engineering constraints including 250 \\(\\pm\\) 50 MW net electric power, tritium breeding ratio \\(>\\)1.1, power exhaust limits and an hour flattop time. Both configurations achieve similar cost-performance Pareto fronts through contrasting design philosophies. PT, while demonstrating resilience to pedestal degradation (compensating for up to 40% reduction), are constrained to larger machines (\\(R_0\\) \\(>\\) 6.5 m) by the narrow operational window between L-H threshold requirements and the research-established power exhaust limit (\\(P_{sol}/R\\) \\(<\\) 15 MW/m). This forces optimization through comparatively reduced magnetic field (\\(\\sim\\)8T). NT configurations exploit their freedom from these constraints to access compact, high-field designs (\\(R_0 \\sim 5.5\\) m, \\(B_0\\) \\(>\\) 12 T), creating natural synergy with advancing HTS technology. Sensitivity analyses reveal that PT's economic viability depends critically on uncertainties in L-H threshold scaling and power handling limits. Notably, a 50% variation in either could eliminate viable designs or enable access to the compact design space. These results suggest configuration selection should be risk-informed: PT offers the lowest-cost path when operational constraints can be confidently predicted, while NT is robust to large variations in constraints and physics uncertainties.