scholarly journals Spin(7) Instantons and Hermitian Yang–Mills Connections for the Stenzel Metric

Author(s):  
Vasileios Ektor Papoulias

AbstractWe use the highly symmetric Stenzel Calabi–Yau structure on $$T^{\star }S^{4}$$ T ⋆ S 4 as a testing ground for the relationship between the Spin(7) instanton and Hermitian–Yang–Mills (HYM) equations. We reduce both problems to tractable ODEs and look for invariant solutions. In the abelian case, we establish local equivalence and prove a global nonexistence result. We analyze the nonabelian equations with structure group SO(3) and construct the moduli space of invariant Spin(7) instantons in this setting. This is comprised of two 1-parameter families—one of them explicit—of irreducible Spin(7) instantons. Each carries a unique HYM connection. We thus negatively resolve the question regarding the equivalence of the two gauge theoretic PDEs. The HYM connections play a role in the compactification of this moduli space, exhibiting a removable singularity phenomenon that we aim to further examine in future work.

2019 ◽  
Author(s):  
Liwei Cao ◽  
Danilo Russo ◽  
Vassilios S. Vassiliadis ◽  
Alexei Lapkin

<p>A mixed-integer nonlinear programming (MINLP) formulation for symbolic regression was proposed to identify physical models from noisy experimental data. The formulation was tested using numerical models and was found to be more efficient than the previous literature example with respect to the number of predictor variables and training data points. The globally optimal search was extended to identify physical models and to cope with noise in the experimental data predictor variable. The methodology was coupled with the collection of experimental data in an automated fashion, and was proven to be successful in identifying the correct physical models describing the relationship between the shear stress and shear rate for both Newtonian and non-Newtonian fluids, and simple kinetic laws of reactions. Future work will focus on addressing the limitations of the formulation presented in this work, by extending it to be able to address larger complex physical models.</p><p><br></p>


2019 ◽  
Author(s):  
Amanda Goodwin ◽  
Yaacov Petscher ◽  
Jamie Tock

Various models have highlighted the complexity of language. Building on foundational ideas regarding three key aspects of language, our study contributes to the literature by 1) exploring broader conceptions of morphology, vocabulary, and syntax, 2) operationalizing this theoretical model into a gamified, standardized, computer-adaptive assessment of language for fifth to eighth grade students entitled Monster, PI, and 3) uncovering further evidence regarding the relationship between language and standardized reading comprehension via this assessment. Multiple-group item response theory (IRT) across grades show that morphology was best fit by a bifactor model of task specific factors along with a global factor related to each skill. Vocabulary was best fit by a bifactor model that identifies performance overall and on specific words. Syntax, though, was best fit by a unidimensional model. Next, Monster, PI produced reliable scores suggesting language can be assessed efficiently and precisely for students via this model. Lastly, performance on Monster, PI explained more than 50% of variance in standardized reading, suggesting operationalizing language via Monster, PI can provide meaningful understandings of the relationship between language and reading comprehension. Specifically, considering just a subset of a construct, like identification of units of meaning, explained significantly less variance in reading comprehension. This highlights the importance of considering these broader constructs. Implications indicate that future work should consider a model of language where component areas are considered broadly and contributions to reading comprehension are explored via general performance on components as well as skill level performance.


2018 ◽  
Vol 24 (3) ◽  
pp. 341-358 ◽  
Author(s):  
Xiaotong Ji ◽  
Yingying Zhang ◽  
Guangke Li ◽  
Nan Sang

Recently, numerous studies have found that particulate matter (PM) exposure is correlated with increased hospitalization and mortality from heart failure (HF). In addition to problems with circulation, HF patients often display high expression of cytokines in the failing heart. Thus, as a recurring heart problem, HF is thought to be a disorder characterized in part by the inflammatory response. In this review, we intend to discuss the relationship between PM exposure and HF that is based on inflammatory mechanism and to provide a comprehensive, updated evaluation of the related studies. Epidemiological studies on PM-induced heart diseases are focused on high concentrations of PM, high pollutant load exposure in winter, or susceptible groups with heart diseases, etc. Furthermore, it appears that the relationship between fine or ultrafine PM and HF is stronger than that between HF and coarse PM. However, fewer studies paid attention to PM components. As for experimental studies, it is worth noting that coarse PM may indirectly promote the inflammatory response in the heart through systematic circulation of cytokines produced primarily in the lungs, while ultrafine PM and its components can enter circulation and further induce inflammation directly in the heart. In terms of PM exposure and enhanced inflammation during the pathogenesis of HF, this article reviews the following mechanisms: hemodynamics, oxidative stress, Toll-like receptors (TLRs) and epigenetic regulation. However, many problems are still unsolved, and future work will be needed to clarify the complex biologic mechanisms and to identify the specific components of PM responsible for adverse effects on heart health.


Author(s):  
Jin-Hwa Lee ◽  
In-Ok Sim

The aim of this study to discover the relationship between psychological well-being, emotional intelligence, willpower, and job-efficacy. The data were collected from 26 May to 30 May 2020 by distributing a questionnaire to 317 clinical nurses with six months of experience in a general hospital located in Seoul. Three hundred copies were collected and used for final data analysis. The results of the study verified that the direct factors of psychological well-being, emotional intelligence, and willpower affect the job-efficacy of clinical nurses and confirmed that emotional intelligence is a mediating factor between psychological well-being and job-efficacy. This study is meaningful in that it proves the necessity of establishing various curriculums focusing on these factors so that nursing students can best perform their duties as professional nurses. In particular, it is suggested that an educational program and curriculum be established that can strengthen the psychological well-being and enhance the emotional intelligence of nursing students. It is expected that such training will equip professional clinical nurses to effectively handle future work in their stress-filled field.


Author(s):  
Donald S Likosky ◽  
Yvon R Baribeau ◽  
Jeremiah R Brown ◽  
Benjamin M Westbrook ◽  
Lawrence J Dacey ◽  
...  

Background: Post-operative low output failure (LOF) is an important contributor to morbidity and mortality during coronary artery bypass grafting (CABG) surgery, and may result from poor myocardial protection. We hypothesized that rates of LOF would vary across surgeons, in part attributed to their myocardial protective strategy. Methods: We identified 11,838 patients undergoing non-emergent, isolated CABG surgery utilizing cardiopulmonary bypass (CPB) at 8 centers in northern New England from 2001-2009. Our cohort included patients with preoperative ejection fractions 40+% and patients operated on by surgeons who performed 80+ CABG procedures during the time period. Patients with preoperative balloon pumps were excluded. LOF was defined as the need for an intra- or post-operative balloon pump, or return to CPB or 2+ inotropes at 48 hours. Predicted rates of LOF were estimated using logistic regression. Results: Case volume varied across surgeons (range: 80-766, median: 344). Overall rate of LOF was 5.3% (return to CPB: 3.2%, balloon pump: 1.8%, inotrope usage: 1.3%). While predicted risk of LOF did not differ across surgeons, p=0.381, observed rates varied from 1.1% to 15.6%, p=0.003 (Figure). Post-operative outcomes, including death (ptrend=0.03) or stroke (ptrend =0.02), significantly increased across surgical LOF strata (low: <2%, medium: 3-9%, high: 10+%). Conclusions There was a 14-fold variability in rates of LOF across surgeons among patients with ejection fractions 40+%. This variability could not be explained by patient case mix. Future work should focus on understanding the relationship between myocardial protective strategy and risk of LOF.


2021 ◽  
Vol 25 (4) ◽  
pp. 1719-1818
Author(s):  
Daniel Greb ◽  
Benjamin Sibley ◽  
Matei Toma ◽  
Richard Wentworth

1999 ◽  
Vol 14 (11) ◽  
pp. 1737-1757 ◽  
Author(s):  
SERGEI M. KUZENKO

We analyze the relationship between the N=2 harmonic and projective superspaces, which are the only approaches developed to describe general N=2 super-Yang–Mills theories in terms of off-shell supermultiplets with conventional supersymmetry. The structure of low energy hypermultiplet effective action is briefly discussed.


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