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1.
INTRODUCTION In recent years theory of extending modules and rings has come to play an important role in the theory of rings and modules. A module is called an extending module (or CS-module) if every submodule is essen- tial in a direct summand, or equivalently, every closed submodule is a direct summand. Although this gen- eralization of injectivity is extremely useful, it does not satisfy some important properties. For example, direct sums of extending modules need not be ex- tending;…  相似文献   

2.
In this paper, we are interested in the following general question: Given a module Mwhich has finite hollow dimension and which has a finite collection of submodules Ki (1≤i≤n) such that M=K1 ... Kn, can we find an expression for the hollow dimension of Min terms of hollow dimensions of modules built up in some way from K1 Kn? We prove the following theorem:Let Mbe an amply supplemented module having finite hollow dimension and let Ki (1≤i≤n) be a finite collection of submodules of Msuch that M=K1 ... Kn. Then the hollow dimension h(M) of Mis the sum of the hollow dimensions of Ki (1≤i≤n) ifand only if Ki is a supplement of K1 ... Ki-1 Ki 1 ... Kn in Mfor each 1≤i≤n.  相似文献   

3.
Frontal asymmetry (FA), the difference in brain activity between the left versus right frontal areas, is thought to reflect approach versus avoidance motivation. This study (2012–2021) used functional near-infrared spectroscopy to investigate if infant (Mage = 7.63 months; N = 90; n = 48 male; n = 75 White) FA in the dorsolateral prefrontal cortex relates to psychopathology in later childhood (Mage = 62.05 months). Greater right FA to happy faces was associated with increased internalizing (η2 = .09) and externalizing (η2 = .06) problems at age 5 years. Greater right FA to both happy and fearful faces was associated with an increased likelihood of a lifetime anxiety diagnosis (R2 > .13). FA may be an informative and early-emerging marker for psychopathology.  相似文献   

4.
将有限表现模限制在平坦维数≤1,得到有限平坦表现模及其性质,利用有限平坦表现模类给出了其Ext-正交模即FFP-内射模,刻画了右F-凝聚环与右F-正则环。在环的几乎优越扩张S≥R下,证明了S为右F-凝聚环当且仅当R为右F-凝聚环,S为右F-正则环当且仅当R为右F-正则环。  相似文献   

5.
陈翔 《闽江学院学报》2013,34(2):8-9,41
利用GI-平坦模与Gorenstein平坦维数给出了平坦模的另一等价刻划,并得到了环R是左Gorenstein半遗传环时,右R模M是GI-平坦模当且仅当M是平坦模;在交换环的条件下利用Hom函子,A函子刻划了GI-平坦模;另外还给出了短正合列上的模的GI平坦维数的关系.  相似文献   

6.
主要研究闭子模都是零化子的模与环,即闭偶模与闭偶环,刻画了闭偶模和闭偶环,给出了n阶矩阵环Mn(R)为闭偶环的一些等价条件,证明了环R是右非奇异右扩张环当且仅当R是右闭偶Baer环。  相似文献   

7.
Child maltreatment is linked to distinct neurophysiological patterns and social‐emotional vulnerability. Relations among maltreatment, relative resting frontal alpha asymmetry, shyness, and psychopathology were examined prospectively. Adolescent girls (age 14–16) who experienced child maltreatment (N = 55) were compared to nonmaltreated controls (N = 25), and returned for 6‐ and 12‐month follow‐ups. Among participants exhibiting relative right frontal asymmetry, maltreated adolescents reported higher shyness than controls at Time 1. Low‐stable and high‐stable shyness trajectories were observed for maltreated participants. Compared to low shy, participants in high‐shy trajectory reported at Time 3: higher neuroticism and generalized anxiety; and lower extraversion if they also exhibited relative right frontal asymmetry. Thus, right frontal brain activity and shyness are involved in social‐emotional vulnerability of adolescents who experienced child maltreatment.  相似文献   

8.
The purpose of this article is to demonstrate constraining the nominal response model in Mplus software to calibrate data under the partial credit model (PCM) and generalized partial credit model (GPCM). Currently, many researchers are uncertain if the PCM and GPCM can be estimated within Mplus. Through model constraint commands in Mplus, we demonstrate that both models can be estimated in recent versions of this software. We present an example of this approach with data from 522 respondents on a subset of items from the Math Self-Efficacy Scale (Betz & Hackett, 1983). It is demonstrated that the presented model code is a viable way of estimating the models in Mplus.  相似文献   

9.
通过fpn^-内射模类来研究模的fpn^-内射覆盖,给出了单的fpn^-内射覆盖的存在性刻画,证明了每个右R-模M都有单的即。一内射覆盖φ：E→M当且仅当环R为右fpn^-遗传环．  相似文献   

10.
This meta-analysis examined the relationship between prenatal maternal stress and/or anxiety and the outcomes of children aged 3 months to 9 years. Of the 8754 studies published before June 2021 that were synthesized, 17 conducted in Western countries were included in the meta-analysis (Ntotal = 23,307; Mmales 54%; Methnicity White 77%, Pacific 15%, African American/Black 10%, Middle Eastern 7%, Eastern 8%). Effect sizes ranged from −0.41 to 0.15. A weak negative association was found between prenatal stress and/or anxiety exposure and children's general intellectual development. Associations varied based on the type of exposure. Findings are limited to developed counties and cannot be generalized to low- and middle-income countries. Directions for maternal prenatal intervention and future studies are discussed.  相似文献   

11.
利用n-余表现模定义了模M的n-余表现维数COPnd(M),刻画了右n-余凝聚环,即R为右n-余凝聚环当且仅当对于任意右R-模M,均有COPnd(M)=COPn+1d(M),并研究了在环扩张下模的n-余表现维数的若干关系式。  相似文献   

12.
This article has 3 objectives that build on each other. First, we demonstrate how to obtain maximum likelihood estimates for dynamic factor models (the direct autoregressive factor score model) with arbitrary T and N by means of structural equation modeling (SEM) and compare the approach to existing methods. Second, we go beyond standard time series analysis (T large and N = 1) and conventional SEM (N large and T = 1 or small) by integrating both approaches. The resulting combined model offers a variety of new modeling options including a direct test of the ergodicity hypothesis, according to which the factorial structure of an individual observed at many time points is identical to the factorial structure of a group of individuals observed at a single point in time. Third, we illustrate the flexibility of SEM time series modeling by extending the approach to account for complex error structures. We end with a discussion of current limitations and future applications of SEM-based time series modeling for arbitrary T and N.  相似文献   

13.
Researchers have found that teacher preparation programs are not universally preparing teacher candidates in concepts associated with the alphabetic principle. Yet, the majority of students with reading disabilities or who struggle with beginning reading have difficulty with phonology and concepts associated with the alphabetic principle. The purpose of this study was to examine the efficacy of a series of multimedia modules on participants' (N = 76) knowledge and skills related to early reading instruction. The multimedia modules covered basic literacy concepts primarily related to phonology and phonics. Results from the experimental, control-group design indicated that the modules were successful in teaching foundational literacy constructs to participants. Thus, multimedia modules may be a promising avenue for providing instruction for teacher candidates. Additional research, however, is needed to ensure mastery of knowledge and to evaluate how principles of effective instruction can guide multimedia module use by teacher educators.  相似文献   

14.
The purpose of this project was to develop Web‐based learning modules that combine (1) animated 3D graphics; (2) 3D models that a student can manipulate independently; (3) passage of time in embryonic development; and (4) animated 2D graphics, including 2D cross‐sections that represent different “slices” of the embryo, and animate in parallel. These elements were presented in two tutorials, one depicting embryonic folding and the other showing development of the nervous system after neural tube formation. The goal was to enhance the traditional teaching format—lecture combined with printed diagrams, text, and existing computer animations—with customized, guided, Web‐based learning modules that surpassed existing resources. To assess module effectiveness, we compared quiz performance of control groups who attended lecture and did not use a supporting module, with study groups who used a module in addition to attending lecture. We also assessed our students' long‐term retention of the material, comparing classes who had used the module with students from a previous year that had not seen the module. Our data analysis suggests that students who used a module performed better than those given only traditional resources if they used the module after they were already somewhat familiar with the material. The findings suggest that our modules—and possibly computer‐assisted‐instruction modules in general—are more useful if used toward the later stages of learning, rather than as an initial resource. Furthermore, our data suggest that the animation aids in long‐term retention. Both medical students at the University of Cincinnati and medical faculty from across the country commented favorably on their experiences with the embryonic development modules. Anat Sci Ed 1:252–257, 2008. © 2008 American Association of Anatomists.  相似文献   

15.
设R是一个环 ,如果对于任意的x ,y∈R ,有xy -yx∈C(R) ,那么下列条件等价 :( 1 )R是强正则环 ;( 2 )R是VonNeumann正则环 ;( 3)R是广义正则环 .设R是半可换环 ,则以下条件等价 :( 1 )R是强正则环 ;( 2 )R的每一个极大的本质的左理想是左GP -内射模 ;( 3)R的每一个极大的本质的右理想是右GP -内射模 .  相似文献   

16.
In this paper, it is proved that the radial pth mean body RpK（p 〉 0） is homothetic to the difference body DK when K is a simplex, Furthermore, the equality Rp（Rq） = Rq（Rp） is established when p 〉 0 and q 〉 0. It is also proved the Brunn-Minkowski inequality of radial pth mean body of simplex and uniqueness property.  相似文献   

17.
模论在现代代数学中起着越来越突出的作用。内射模是模论中的一个有着基本重要性的概念。拟内射模是比内射模更广的一类模。本文讨论了拟内射模的性质和刻划。并应用它给出了几种环的拟内射性刻划。在一般教科书中这些环都是用内射性来给出其外刻划的。  相似文献   

18.
Efficiency gains arising from the use of electronic marking tools that allow tutors to select comments from a statement bank are well documented, but how students use this type of feedback remains under explored. Natural science students (N = 161) were emailed feedback reports on a spreadsheet assessment that included an invitation to reply placed at different positions. Outcomes suggest that students either read feedback completely, or not at all. Although mean marks for repliers (M = 75.5%, N = 39) and non-repliers (M = 57.2%, N = 68) were significantly different (p < .01), these two groups possessed equivalent attendance records and similar submission rates and performances in a contemporaneous formatively assessed laboratory report. Notably, average marks for a follow-up summative laboratory report, using the same assessment criteria as the formative task, were 10% higher for students who replied to the original invite. It is concluded that the repliers represent a group of assessment literate students, and that statement bank feedback can foster learning: a simple ‘fire’ analogy for feedback is advanced that advocates high-quality information on progress (fuel) and a curricular atmosphere conducive to learning (oxygen). However, only if students are assessment literate (ignition) will feedback illuminate.  相似文献   

19.
This systematic review and meta-analysis considered evidence of guided play compared to direct instruction or free play to support children's learning and development. Interventions from 39 studies were reviewed (published 1977–2020); 17 were included in meta-analysis (Ntotal = 3893; Mchildage = 1–8 years; Mgirls 49.8%; Methnicity White 41%, African American/Black 28%, Hispanic 19%). Guided play had a greater positive effect than direct instruction on early maths skills (g = 0.24), shape knowledge (g = 0.63), and task switching (g = 0.40); and than free play on spatial vocabulary (g = 0.93). Differences were not identified for other key outcomes. Narrative synthesis highlighted heterogeneity in the conceptualization and implementation of guided play across studies.  相似文献   

20.
William M. Kinney 《PRIMUS》2017,27(8-9):880-888
Abstract

Educational modules can play an important part in revitalizing the teaching and learning of complex analysis. At the Westmont College workshop on the subject in June 2014, time was spent generating ideas and creating structures for module proposals. Sharing some of those ideas and giving a few example modules is the main purpose of this paper. The author has started to construct Mathematica-based educational modules for complex analysis, one of which is available in the online repository of supplemental materials for this article. The author has also begun work on a website called The Complex Moduli Project to make modules in complex analysis available worldwide, and invites others to join him in this endeavor.  相似文献   

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