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1.
1 Introduction We consider the finite digraphs that do not havemultiple arcs or loops , but pairs of opposite arcs areallowed.LetD=(V,A) be a digraph , whereVisthe set of vertices andAis the set of arcs .If there isan arc (x,y) fromxtoy,thenthe vertexxis … 相似文献
2.
Objective： The aim of this study was to investigate subgingival infection frequencies ofPorphyromonas gingivalis and Actinobacillus actinomycetemcomitans strains with genetic variation in Chinese chronic periodontitis （CP） patients and to evaluate its correlation with clinical parameters. Methods： Two multiplex polymerase chain reaction （PCR） assays were developed to detect the 16SrDNA, collagenase （prtC） and fimbria （fimA） genes of P. gingivalis and the 16SrDNA, leukotoxin （lktA） and fimbria-associated protein （fap） genes ofA. actinomycetemcomitans in 60 sulcus samples from 30 periodontal healthy subjects and in 122 subgingival plaque samples from 61 patients with CP. The PCR products were further T-A cloned and sent for nucleotide sequence analysis. Results： The 16SrDNA,prtC andfimA genes ofP. gingivalis were detected in 92.6%, 85.2% and 80.3% of the subgingival plaque samples respectively, while the 16SrDNA, lktA andfap genes ofA. actinomycetemcomitans were in 84.4%, 75.4% and 50.0% respectively. Nucleotide sequence analysis showed 98.62%-100% homology of the PCR products in these genes with the reported sequences. P. gingivalis strains with prtC＋/fimA＋ and A. actinomycetemcomitans with lktA＋ were predominant in deep pockets （〉6 mm） or in sites with attachment loss 〉5 mm than in shallow pockets （3-4 mm） or in sites with attachment loss 〈2 mm （P〈0.05）. P. gingivalis strains withprtC＋/fimA＋ also showed higher frequency in gingival index （GI）=3 than in GI=1 group （P〈0.05）. Conclusion： Infection ofP. gingivalis with prtC＋/fimA＋ and A. actinomycetemcomitans with lktA＋ correlates with periodontal destruction of CP in Chinese. Nonetheless P. gingivalis fim4, prtC genes and A. actinomycetem- comitans lktA gene are closely associated with periodontal destruction, while A. actinomycetemcomitansfap gene is not. 相似文献
3.
Let R be a ring, a ,b ∈ R, ( D , α ) and (G , β ) be two generalized derivations of R . It is proved that if aD ( x ) = G ( x )b for all x ∈ R, then one of the following possibilities holds: (i) If either a or b is contained in C , then α = β= 0 and there exist p , q ∈ Qr ( RC) such that D ( x )= px and G ( x )= qx for all x ∈ R;(ii) If both a and b are contained in C , then either a = b= 0 or D and G are C-linearly dependent;(iii) If neither a nor b is contained in C , then there exist p , q ∈ Qr ( RC) and w ∈ Qr ( R) such that α ( x ) = [ q ,x] and β ( x ) = [ x ,p] for all x ∈ R, whence D ( x )= wx-xq and G ( x )= xp + avx with v ∈ C and aw-pb= 0. 相似文献
4.
Let Γd2nbe the set of trees with a given diameter d having a perfect matching,where 2n is the number of vertex.For a tree T in Γd2n,let Pd+1be a diameter of T and q = d m,where m is the number of the edges of perfect matching inPd+1.It can be found that the trees with minimal energy in Γd2nfor four cases q = d 2,d 3,d 4,[d2],and two remarks aregiven about the trees with minimal energy in Γd2nfor2d 33q d 5 and [d2] + 1 q2d 33 1. 相似文献
5.
Chris Loynes 《Journal of Adventure Education & Outdoor Learning》2013,13(2):113-125
This research highlights the learning of female offenders on a 20-day tailor-made experiential adventure education course (Women in Action) delivered by Outward Bound New Zealand. The aims of the course were to increase self-awareness, to develop an understanding of the concept of choice and self responsibility, to improve communication skills and to effectively influence others. Twenty-seven women were interviewed immediately after the course and 14 of these, three months post-course. Most women indicated that their self-confidence had increased and they had become more self-aware. Key factors in facilitating learning opportunities for the women were the instructors and the course environment both physical and social. The holistic course approach provided physical, creative, emotional and reflective opportunities, enabling all the women to develop personally. The challenge of applying their learning on return to prison was highlighted by some participants.
Never did I think that My life could be changed In so many ways. But the challenges I've faced From being here Lord I Know That I can make it. Cos I gotta keep on Moving on in life Won't let my spirit fall Walk on walk on. Some people tell me I'd never change. But now I've seen the light More clear in every kind of way I'm alive today No more worries on my shoulders I'm gonna make it Oh yes I am. Cos I gotta keep on Moving on in life Won't let my spirit fall Walk on walk on. (Poem by T – Women in Action participant) 相似文献
6.
AtCRE1 is known to be a cytokinin receptor inArabidopsis. TheAtCRE1 protein contains CHASE domain at the N-terminal part, followed by a transmitter (histidine kinase) domain and two receiver
domains. The N-terminal CHASE domain ofAtCRE1 contains putative recognition sites for cytokinin. Five CHASE domains containing proteins were found in rice,osCRL1a,OsCRL1b,OsCRL2,OsCRL3, andOsCRL4.OsCRL1a,OsCRL1b,OsCRL2 andOsCRL3 contain the four domains existing inCRE1, whereasOsCRL4 only contains the CHASE domain and a putative Ser/Thr protein kinase domain. The authors cloned the encoding geneOsCRL4 and found that it represents a new member of the cytokinin receptor protein in rice.
Project supported by the National Natural Science Foundation of China 相似文献
7.
This preliminary study examines the utility of the Community Engagement Commitment Scale and reports on factors that predict student-teachers' commitment to community engagement in their second year of study at a South African university. Independent variables included Dalbert's personal belief in a just world, an adaptation of Rusbult et al.'s original predictors of Commitment level (Satisfaction, Quality of alternatives, Investment size) and a new factor, Meaningfulness. The latter factor is based theoretically on the work of Lieberman and Heine, Proulx and Vohs and was included to study the extent to which identity-expression could be related to Commitment level. We administered the Community Engagement Commitment Scale on a non-random sample of 414 student-teachers in their second year of study, who all participated in compulsory community engagement project. The results support a four-factor model of Commitment with Meaningfulness, Quality of alternatives and Investment as predictors of Commitment level. Surprisingly, all the Satisfaction items loaded with the Commitment level items on one factor. Together, Meaningfulness, Quality of alternatives and Investment accounted for approximately two-thirds of the variance in Commitment level. Significant (p?Meaningfulness and Commitment level. The results of the study suggest the importance of studying meaningfulness as an additional predictor of Commitment level in community engagement contexts. 相似文献
8.
Ali Tarhini Kate Hone Xiaohui Liu Takwa Tarhini 《Interactive Learning Environments》2017,25(3):306-328
In this study, we examine the effects of individual-level culture on the adoption and acceptance of e-learning tools by students in Lebanon using a theoretical framework based on the Technology Acceptance Model (TAM). To overcome possible limitations of using TAM in developing countries, we extend TAM to include subjective norms (SN) and quality of work life constructs as additional constructs and a number of cultural variables as moderators. The four cultural dimensions of masculinity/femininity (MF), individualism/collectivism, power distance and uncertainty avoidance were measured at the individual level to enable them to be integrated into the extended TAM as moderators and a research model was developed based on previous literature. To test the hypothesised model, data were collected from 569 undergraduate and postgraduate students using e-learning tools in Lebanon via questionnaire. The collected data were analysed using the structural equation modelling technique in conjunction with multi-group analysis. As hypothesised, the results of the study revealed perceived usefulness (PU), perceived ease of use (PEOU), SN and quality of work life to be significant determinants of students’ behavioural intention (BI) towards e-learning. The empirical results also demonstrated that the relationship between SN and BI was particularly sensitive to differences in individual-cultural values, with significant moderating effects observed for all four of the cultural dimensions studied. Some moderating effects of culture were also found for both PU and PEOU, however, contrary to expectations the effect of quality of work life was not found to be moderated by MF as some previous authors have predicted. The implications of these results to both theory and practice are explored in the paper. 相似文献
9.
LetH
n
be the set of real algebraic polynomials of degreen, whose zeros all lie in the interval [−1,1]. The well known Turán type inequalities tell us that forf(x)∈H
n
, it holds ‖f′‖≥C√n‖f‖. This note deals with the weighted Turán type inequalities with the weights having inner singularities underL
p
norm for 0<p≤∞. Our results essentially extend the result of Wang and Zhou (2002), and the method used in this paper is simpler and more
direct than that of Wang and Zhou (2002). The results and methods have their own values in approximation theory and computation. 相似文献
10.
Pigeons were trained in a duration-comparison procedure to peck one key if the comparison duration (c) was 1 sec shorter than a standard duration (s), and another key if c was 1 sec longer than s. During training, the s-c delay was 1 sec, and the total duration of an s-c pair was not predictive of the correct choice. In Experiment 1, during equal-duration pair test trials, pigeons increasingly
responded long (i.e., c τ s) as the s-c delay was lengthened. In Experiment 2, we demonstrated that s affected long responding on equal-duration test trials, even at the 8-sec s-c delay. In Experiment 3, long responding increased as the s-c delay was lengthened, even when stimulus conditions during the s-c delay differed from those during the intertrial interval (ITI). Additional analyses indicated that it was unlikely that the
increase in long responding was due to the pigeons’ adding the s-c delay to c and comparing the total against the duration of s. The increase in long responding with an increase in s-c delay is more consistent with subjective shortening of s than with confusion between the s-c delay and the ITI. 相似文献
11.
A hybrid two-stage flowshop scheduling problem was considered which involves m identical parallel machines at Stage 1 and a burn-in processor M at Stage 2, and the makespan was taken as the minimization objective. This scheduling problem is NP-hard in general. We divide it into eight subcases. Except for the following two subcases： （1） b≥ an, max{m, B} 〈 n; （2） a1 ≤ b ≤ an, m ≤ B 〈 n, for all other subcases, their NP-hardness was proved or pointed out, corresponding approximation algorithms were conducted and their worst-case performances were estimated. In all these approximation algorithms, the Multifit and PTAS algorithms were respectively used, as the jobs were scheduled in m identical parallel machines. 相似文献
12.
Jigna Nawani Julia Rixius Birgit J. Neuhaus 《International Journal of Science Education》2016,38(12):1882-1903
Empirical analysis of secondary biology classrooms revealed that, on average, 68% of teaching time in Germany revolved around processing tasks. Quality of instruction can thus be assessed by analyzing the quality of tasks used in classroom discourse. This quasi-experimental study analyzed how teachers used tasks in 38 videotaped biology lessons pertaining to the topic ‘blood and circulatory system’. Two fundamental characteristics used to analyze tasks include: (1) required cognitive level of processing (e.g. low level information processing: repetiition, summary, define, classify and high level information processing: interpret-analyze data, formulate hypothesis, etc.) and (2) complexity of task content (e.g. if tasks require use of factual, linking or concept level content). Additionally, students’ cognitive knowledge structure about the topic ‘blood and circulatory system’ was measured using student-drawn concept maps (N?=?970 students). Finally, linear multilevel models were created with high-level cognitive processing tasks and higher content complexity tasks as class-level predictors and students’ prior knowledge, students’ interest in biology, and students’ interest in biology activities as control covariates. Results showed a positive influence of high-level cognitive processing tasks (β?=?0.07; p?.01) on students’ cognitive knowledge structure. However, there was no observed effect of higher content complexity tasks on students’ cognitive knowledge structure. Presented findings encourage the use of high-level cognitive processing tasks in biology instruction. 相似文献
13.
Consider the positive d-dimensional lattice d (d≥2) with partial ordering ≤, let {XK; K ∈ d } be i.i.d. random vari- ables taking values in a real separable Hilbert space (H, ||·||) with mean zero and covariance operator ∑, and set partial sums SN =∑K≤NXK, K , N ∈ d . Under some moment conditions, we obtain the precise asymptotics of a kind of weighted infinite series for partial sums SN as ε 0 by using the truncation and approximation methods. The results are related to the convergence rates of the law of the logarithm in Hilbert space, and they also extend the results of (Gut and Spǎtaru, 2003). 相似文献
14.
Shailesh A. Shirali 《Resonance》2007,12(7):27-43
For non-negative integers k, n, let P
k
(n) denote the sum {fx27-1}. We show by two different means that if k ≥ 3 and odd, then n
2(n+1)2 iss a factor of the polynomial P
k
(n); and if k ≥ 2 and even, then n (n+1) (2n+1) is a factor of the polynomial P
k
(n). We also derive a relatively unknown result first obtained by Johann Faulhaber in the 17th century.
Shailesh Shirali has been at Rishi Valley School, Andhra Pradesh (Krishnamurti Foundation India) since the 1980’s. He has
a deep interest in teaching and writing about mathematics at the high school/post school levels, with particular emphasis
on problem solving and on historical aspects of the subject. He has been involved in the Mathematics Olympiad movement at
the national and international level for the past two decades. He is the author of several expository books and articles aimed
at interested high school students. 相似文献
15.
Private supplementary tutoring became a widespread phenomenon in Japan during the 1960s. Since then, institutions providing tutoring known as juku have provided a wide range of services to supplement mainstream education. During decades of development, the shapes and functions of juku have changed in response to changes in schooling. Government attitudes towards juku have also shifted from rejection to collaboration, partly because juku have become so entrenched in Japanese society and can no longer be excluded from public decision-making processes. Collaboration between schools and juku is becoming increasingly evident in a series of neoliberal policy choices and socio-demographic changes. Patterns underline a government move to mobilize profit-driven juku to serve the public good. The inclusion of juku in public schooling necessitates reconceptualization of the roles of juku in the educational landscape. This article presents a conceptual framework based on an overview of the changing relationships between juku and schooling. It also identifies challenges in the collaboration, and explores implications for future relationships between mainstream and shadow education. 相似文献
16.
17.
Díaz MP Rizo OD Díaz AL Aparicio EE Díaz RR 《Journal of Zhejiang University. Science. B》2006,7(12):947-956
A discriminant method for optimizing activity in nuclear medicine studies is validated by comparison with ROC （received operating characteristic）-curves. The method is tested in 21 single photon emission computerized tomography （SPECT）, performed with a cardiac phantom. Three different lesions （Lb L2 and L3） were placed in the myocardium-wall by pairs fbr each SPECT. Three activities （84, 37 or 18.5 MBq） of 99mTc were used as background. Linear discriminant analysis was used to select the parameters that characterize image quality among the measured variables in the images [（Background-to-Lesion （B/Li） and Signal-to-Noise （S/N） ratios）]. Two clusters with different image quality （P=0.021 ） were obtained. The ratios B/Lj, B/L2 and B/L3 are the parameters used to construct the function with 100% of cases correctly classified into the clusters. The value of 37 MBq was the lowest tested activity for which good results for the B/Li ratios were obtained. The result coincides with the applied ROC-analysis （r=0.89）. 相似文献
18.
Mei-Shiu Chiu 《International Journal of Science and Mathematics Education》2012,10(1):163-191
The aim of the present study was to identify children’s conceptions of learning mathematics and to assess the identified conceptions.
Children’s conceptions are identified by interviewing 73 grade 5 students in Taiwan. The interviews are analyzed using qualitative
data analysis methods, which results in a structure of 5 major conceptions, each having 2 subconceptions: constructivist (interest and understanding), interpretivist (liberty and innovation), objectivist (academic goal and perseverance), nativist (confidence and anxiety (reverse)), and pragmatist (vocational goal and application). The conceptions are assessed with a self-developed questionnaire, titled “the Conception of Learning Mathematics Questionnaire”
(CLMQ), which is administered to 513 grade 5 students in Taiwan and examined with a reliability measure, confirmatory factor
analysis, and correlations with 2 criteria: mathematics achievement and approaches to learning mathematics. The results show
that the CLMQ has desirable internal consistency reliability and construct validity. The conceptions are also sensibly in
relation to the 2 criteria, suggesting that the CLMQ is a valid measure for evaluating the quality of children’s learning
mathematics in relation to teaching contexts. 相似文献
19.
Philip A. Trostel 《Research in higher education》2010,51(3):220-247
This study quantifies one part of the return to U.S. public investment in college education, namely, the fiscal benefits associated
with greater college attainment. College graduates pay much more taxes than those not going to college. Government expenditures
are also much less for college graduates than for those without a college education. Indeed, over an average lifetime, total
government spending per college degree is negative. That is, direct savings in post-college government expenditures (conservatively,
about 85,000 per four-year-equivalent degree over an average lifetime) are greater than government expenditures on higher education (generously, about85,000 per four-year-equivalent degree over an average lifetime) are greater than government expenditures on higher
education (generously, about 74,500 per degree). Plus, the direct extra tax revenues from college graduates alone (roughly
$471,000 per degree over a lifetime) are more than six times the gross government cost per college degree. The average real
fiscal internal rate of return on government investment in college students is conservatively estimated to be 10.3%. 相似文献
20.
Clare Richards 《Pastoral Care in Education》2018,36(1):44-56
Considers the experiences of designated safeguarding staff in primary aged schools (4–11 years). The study used semi-structured interviews to explore with professionals their experiences of multi-agency working to safeguard children, of factors in making decisions around reporting concerns to statutory social work services and their role in delivering early help services in one region of the U.K. Professionals raised concerns about their understanding of decisions made by social workers, but nevertheless said that these decisions affected their future reporting of safeguarding concerns. Professionals raised concern about how current safeguarding processes triage concerns around neglect, and as the effect was cumulative, felt that it could be minimised or overlooked. 相似文献