低磁场回旋速调管的空间电荷效应

本文建立了考虑直流空间电荷效应和交流空间电荷效应的低磁场(大回旋半经)回旋速调管扰动理论。在漂移区中考虑直流空间电荷场的影响。我们发现电子运动在该区服从一振荡方程;进一步在输出腔中计及了交流空间电荷场对注一波换能的影响。文中求得了相应的电子群聚、注一波互作用功率及增益的表达式,并进行了讨论。     

A randomized Baumgartner statistic for multivariate two-sample testing hypothesis

In this paper, multivariate two-sample testing problems were examined based on the Jure?ková–Kalina's ranks of distances. The multivariate two-sample rank test based on the modified Baumgartner statistic for the two-sided alternative was proposed. The proposed statistic was a randomized statistic. Simulations were used to investigate the power of the suggested statistic for various population distributions.     

论高校教师队伍建设

鉴于高校教师队伍在理想信念、教育思想、敬业精神、文化素养、育人意识、教育手段等素质方面存在的问题 ,我们必须采取有力措施 ,加强培训并改变管理机制 ,建设一支高素质的教师队伍。     

孟浩然入京考实

唐代山水田园派诗人孟浩然,因谋取功名,一生曾三入长安。开元十一年冬,孟浩然因中书令张说之荐而首入长安,并写了著名的《赴京途中遇雪》一诗。开元十六年秋,孟浩然因"应进士"举二入长安,并与王维相识于京师。开元十九年一月,唐玄宗率文武百官"幸"东都,孟浩然闻之,乃于翌年春由襄阳而至,之后由洛阳三入长安。     

Resilience in low-income African American women living and aging with HIV

Women are living with HIV into middle and older age and are likely to face multiple comorbidities and stressors as they age. This study focused on understanding how women who experience multiple forms of oppression and ongoing adversity are still able to adapt and stand strong. Using a theoretical framework of resilience and a feminist research ideology, interviews of eight middle-aged and older African American women living with HIV were analyzed. Despite experiences of HIV-related discrimination, trauma, and violence, these women demonstrated a remarkable ability to adapt and maintain support. Implications for research and practice are discussed.     

Asymptotic theory for maximum likelihood estimates in reduced-rank multivariate generalized linear models

Reduced-rank regression is a dimensionality reduction method with many applications. The asymptotic theory for reduced rank estimators of parameter matrices in multivariate linear models has been studied extensively. In contrast, few theoretical results are available for reduced-rank multivariate generalized linear models. We develop M-estimation theory for concave criterion functions that are maximized over parameter spaces that are neither convex nor closed. These results are used to derive the consistency and asymptotic distribution of maximum likelihood estimators in reduced-rank multivariate generalized linear models, when the response and predictor vectors have a joint distribution. We illustrate our results in a real data classification problem with binary covariates.     

Properties of the weighted log‐rank test in the design of confirmatory studies with delayed effects

Proportional hazards are a common assumption when designing confirmatory clinical trials in oncology. This assumption not only affects the analysis part but also the sample size calculation. The presence of delayed effects causes a change in the hazard ratio while the trial is ongoing since at the beginning we do not observe any difference between treatment arms, and after some unknown time point, the differences between treatment arms will start to appear. Hence, the proportional hazards assumption no longer holds, and both sample size calculation and analysis methods to be used should be reconsidered. The weighted log‐rank test allows a weighting for early, middle, and late differences through the Fleming and Harrington class of weights and is proven to be more efficient when the proportional hazards assumption does not hold. The Fleming and Harrington class of weights, along with the estimated delay, can be incorporated into the sample size calculation in order to maintain the desired power once the treatment arm differences start to appear. In this article, we explore the impact of delayed effects in group sequential and adaptive group sequential designs and make an empirical evaluation in terms of power and type‐I error rate of the of the weighted log‐rank test in a simulated scenario with fixed values of the Fleming and Harrington class of weights. We also give some practical recommendations regarding which methodology should be used in the presence of delayed effects depending on certain characteristics of the trial.     

Stochastic Bounds with a Low Rank Decomposition

We investigate how we can bound a discrete time Markov chain (DTMC) by a stochastic matrix with a low rank decomposition. In the first part of the article, we show the links with previous results for matrices with a decomposition of size 1 or 2. Then we show how the complexity of the analysis for steady-state and transient distributions can be simplified when we take into account the decomposition. Finally, we show how we can obtain a monotone stochastic upper bound with a low rank decomposition.     

A simulation study on power comparisons for group sequential tests of non-parametric statistics

In this article, a group sequential test (GST) of non-parametric statistics for survival data is briefly reviewed. An asymptotic joint distribution of the test statistics, obtained after each interim analysis, is given to illustrate the applicability of the critical values of the GST procedures. It should be noted that censored observations are generally seen in survival data. Therefore, if one makes power calculations irrespective of censoring, reliable results may not be achieved, due to the lack of information about the censoring structure. A wide simulation study, covering different censoring rates and tied observations, is conducted to make the power comparisons under various scenarios. The simulation results are interpreted and compared with the results obtained by using power analysis and sample size (PASS) software.     

发展低空消费新业态的现实困境与实践进路

发展和培育低空消费新业态,是顺应市场经济规律、促进低空经济良性循环的必由之路,对促进低空产业链发育、转变经济发展方式、满足群众消费需求、推动低空经济健康可持续发展具有重要意义。我国低空消费在改革驱动下经历了严格管控、初步探索和快速培育三个阶段,虽然取得了一定成效,但低空消费业态发展仍处于初级阶段。当前,我国低空消费面临低空生产与低空消费结构失衡、低空消费与低空设施空间错配、低空活动与业态培育效率损失三大困境,需要从政策、资源、技术和文化等四方面共同发力,实现低空消费的跨越式发展,打造具有中国特色的低空消费业态和航空文化。