271 research outputs found

    Monotone Tree-Based GAMI Models by Adapting XGBoost

    Full text link
    Recent papers have used machine learning architecture to fit low-order functional ANOVA models with main effects and second-order interactions. These GAMI (GAM + Interaction) models are directly interpretable as the functional main effects and interactions can be easily plotted and visualized. Unfortunately, it is not easy to incorporate the monotonicity requirement into the existing GAMI models based on boosted trees, such as EBM (Lou et al. 2013) and GAMI-Lin-T (Hu et al. 2022). This paper considers models of the form f(x)=∑j,kfj,k(xj,xk)f(x)=\sum_{j,k}f_{j,k}(x_j, x_k) and develops monotone tree-based GAMI models, called monotone GAMI-Tree, by adapting the XGBoost algorithm. It is straightforward to fit a monotone model to f(x)f(x) using the options in XGBoost. However, the fitted model is still a black box. We take a different approach: i) use a filtering technique to determine the important interactions, ii) fit a monotone XGBoost algorithm with the selected interactions, and finally iii) parse and purify the results to get a monotone GAMI model. Simulated datasets are used to demonstrate the behaviors of mono-GAMI-Tree and EBM, both of which use piecewise constant fits. Note that the monotonicity requirement is for the full model. Under certain situations, the main effects will also be monotone. But, as seen in the examples, the interactions will not be monotone.Comment: 12 page

    The Hamiltonian BRST quantization of a noncommutative nonabelian gauge theory and its Seiberg-Witten map

    Full text link
    We consider the Hamiltonian BRST quantization of a noncommutative non abelian gauge theory. The Seiberg-Witten map of all phase-space variables, including multipliers, ghosts and their momenta, is given in first order in the noncommutative parameter Ξ\theta. We show that there exists a complete consistence between the gauge structures of the original and of the mapped theories, derived in a canonical way, once we appropriately choose the map solutions.Comment: 10 pages, Latex. Address adde

    Gender-based difference in early mortality among patients with ST-segment elevation myocardial infarction: insights from Kermanshah STEMI Registry.

    Get PDF
    Introduction: This study aimed to evaluate the in-hospital mortality of patients with ST-segment elevation myocardial infarction (STEMI), according to gender and other likely risk factors. Methods: This study reports on data relating to 1,484 consecutive patients with STEMI registered from June 2016 to May 2018 in the Western Iran STEMI Registry. Data were collected using a standardized case report developed by the European Observational Registry Program (EORP). The relationship between in-hospital mortality and potential predicting variables was assessed multivariable logistic regression. Differences between groups in mortality rates were compared using chi-square tests and independent t-tests. Results: Out of the 1484 patients, 311(21%) were female. Women were different from men in terms of age (65.8 vs. 59), prevalence of hypertension (HTN) (63.7% vs. 35.4%), diabetes mellitus (DM) (37.7% vs. 16.2%), hypercholesterolemia (36.7% vs. 18.5%) and the history of previous congestive heart failure (CHF) (6.6% vs. 3.0%). Smoking was more prevalent among men (55.9% vs. 13.2%). Although the in-hospital mortality rate was higher in women (11.6% vs. 5.5%), after adjusting for other risk factors, female sex was not an independent predictor for in-hospital mortality. Multivariable analysis identified that age and higher Killip class (≄II) were significantly associated with in-hospital mortality rate. Conclusion: In-hospital mortality after STEMI in women was higher than men. However, the role of sex as an independent predictor of mortality disappeared in regression analysis. The gender based difference in in-hospital mortality after STEMI may be related to the poorer cardiovascular disease (CVD) risk factor profile of the women

    BRST Quantization of Noncommutative Gauge Theories

    Get PDF
    In this paper, the BRST symmetry transformation is presented for the noncommutative U(N) gauge theory. The nilpotency of the charge associated to this symmetry is then proved. As a consequence for the space-like non-commutativity parameter, the Hilbert space of physical states is determined by the cohomology space of the BRST operator as in the commutative case. Further, the unitarity of the S-matrix elements projected onto the subspace of physical states is deduced.Comment: 20 pages, LaTeX, no figures, one reference added, to appear in Phys. Rev.
    • 

    corecore