知母染色体核型的研究

  A karyotypical analysis of Anemarrhena asphodeloides Bung. of the monotypic genus Anemarrhena Bung. (Liliaceae) was carried out for the first time. The number of chromo- somes in root-tip cell of the species was found to be 22, agreeing with that reported by Sato[12], although inconsistent in some other respects, such as position of  centromeres, length of chromosomes, and nucleoli, etc. (Table 1 ). According to the terminology defined by Levan et al.［8］, the karyotype formula is therefore 2n=22=2sm (SAT)+2sm+18m. Photomicrographs of the chromosome complements and idiogram of the karyotype are given   Fig. 1 and 2).       The karyotype of Anemarrhena asphodeloides shows explicitly to be asymmetrical, with three pairs of long chromosomes and eight pairs of short chromosomes. This specialized feature, when considered together with the rare occurrence of the basic chromosome number of 11 of the genus within the Tribe Asphodeleae of Liliaceae (see Table 1), suggests that the genus Anemarrhena is probably a rather specialized one, which has scarcely any intimate relationship with the other genera of the above tribe. The fact that this specialized karyotype is associated with certain trends of morphological specialization, such as flowers possessing three stamens only, gives support to the above suggestion. But, it is impossible to draw a more precise conclusion without a more thorough and comprehensive investigation of the species in question.     

Examining the effects of combining self-explanation principles with an educational game on learning science concepts

Educational researchers have indicated that although computer games have the potential to promote students’ motivation and engagement, the work on how to design effective games that fulfil educational purposes is still in its infancy. This study aimed to examine how integration of self-explanation into a computer game affected primary schoolers’ acquisition of light and shadow concepts. The participants were randomly assigned to either an experimental group or a control group and played a computer game with or without self-explanation prompts individually as a treatment. Students’ conceptual understanding was evaluated through a pretest and a posttest administered right after the treatment. The results revealed that by controlling the pretest scores, students who played the game with self-explanation features did not outperform those who played the game without any prompts in the posttest. Further analyses of the experimental group students’ responses to the self-explanation prompts also indicated that the students with more correct responses to the prompts did not perform better than those with lower accuracy rates. The deficits in the use of self-explanation prompts are identified, and possible improvements to enhance the function of self-explanation in educational games are proposed.     

Examining the impact of educational technology courses on pre-service teachers’ development of technological pedagogical content knowledge

The purpose of this qualitative study was to examine the impact of educational technology courses on pre-service teachers’ development of knowledge of technology integration in a teacher preparation program in the USA. The present study was conducted with eight pre-service teachers enrolled in the elementary teacher education program at a large university in the mid-western USA. Data sources included interviews, documents, and observations. The findings identified knowledge of technology integration the pre-service teachers developed and identified knowledge of technology integration needed in the technology integration courses. The present study provided a number of suggestions on different activities that could be built into educational technology courses to better prepare pre-service teachers to teach with technology.     

Whole Class Dialogic Discussion Meets Taiwan’s Physics Teachers: Attitudes and Culture

There is a distance between the power that whole class dialogic discussions (WCDD) may offer to the science class and their use in practice. Teachers’ attitudes toward WCDD are part of the problem. The aims of this study were twofold: (a) to examine Taiwanese physics teachers’ attitudes toward WCDD by considering cultural perspectives and describe how these attitudes changed as a result of a special workshop designed for this purpose, and (b) to report on how these attitudes should be taken into account in designing such workshops in the future. Nine experienced physics teachers participated in the WCDD workshop. The workshop was based on the WCDD model developed by Eshach (2010). Inductive analyses were performed on interviews with the teachers and their students, which were composed of 36 questions and developed specially for the purpose of this study, yielded the following categories: (1) In-school reasons for opposing WCDD—reasons belonging to school ways/tradition of teaching that may cause barriers to WCDD implementation; (2) External Factors—cultural reasons relating to Taiwanese views concerning education in general, which cause barriers to WCDD implementation; and (3) Cognitive aspect—refers to what teachers know about WCDD. The paper concludes with a discussion on what should be done in order to successfully bring WCDD to the Taiwanese physics class.     

Blocking in autoshaped lever-pressing procedures with rats

Rats will approach and contact a lever whose insertion into the chamber signals response-independent food delivery. This “autoshaping” or “sign-tracking” phenomenon has recently attracted considerable attention as a platform for studying individual differences in impulsivity, drug sensitization, and other traits associated with vulnerability to drug addiction. Here, we examined two basic stimulus selection phenomena—blocking and overshadowing—in the autoshaped lever pressing of rats. Blocking and overshadowing were decidedly asymmetrical. Previously reinforced lever-extension conditioned stimuli (CSs) completely blocked conditioning to auditory cues (Exps. 1 and 2), and previously nonreinforced lever-extension CSs overshadowed conditioning to auditory cues. By contrast, conditioning to lever-extension CSs was not blocked by either auditory (Exp. 3) or lever-insertion (Exp. 4) cues, and was not overshadowed by auditory cues. Conditioning to a lever-insertion cue was somewhat overshadowed by the presence of another lever, especially in terms of food cup behavior displayed after lever withdrawal. We discuss several frameworks in which the apparent immunity of autoshaped lever pressing to blocking might be understood. Given evidence that different brain systems are engaged when different kinds of cues are paired with food delivery, it is worth considering the possibility that interactions among them in learning and performance may follow different rules. In particular, it is intriguing to speculate that the roles of simple cue–reinforcer contiguity, as well as of individual and aggregate reinforcer prediction errors, may differ across stimulus classes.     

Global real-time optimization by output-feedback extremum-seeking control with sliding modes

This paper addresses the design of a sliding mode based extremum-seeking controller for a class of single-input–single-output (SISO) uncertain nonlinear systems with unmatched and state-dependent strong nonlinearities. We demonstrate that it is possible to achieve an arbitrarily small neighborhood of the desired optimal point using only output-feedback. The key idea is the combination of a periodic switching function with a norm state observer. As an important advantage, we show that the proposed scheme achieves extremum-seeking for all initial conditions, i.e., the real-time optimization algorithm has global convergence properties. An application to a simple nonderivative optimizer illustrates the viability of the proposed approach.     

The Role of Computer Simulation in an Inquiry-Based Learning Environment: Reconstructing Geological Events as Geologists

Several researchers have investigated the effects of computer simulations on students’ learning. However, few have focused on how simulations with authentic contexts influences students’ inquiry skills. Therefore, for the purposes of this study, we developed a computer simulation (FossilSim) embedded in an authentic inquiry lesson. FossilSim integrated data from real field investigations with geological laws for identifying the sequence of geological events. Data were collected from two experiments to examine ninth graders’ abilities for reconstructing a sequence of geological events with the aid of FossilSim. The sample groups in Experiments 1 and 2 were 58 and 11 ninth graders, respectively. The results indicated that the authentic inquiry lesson promoted the development of students’ inquiry skills. In addition, FossilSim played a key role in engaging students to apply geological laws, make multi-scale observations, and clarify their ideas about geological time.     

Undergraduates’ intentions to take examinations for professional certification: examinations of four competing models

Previous research on professional certification has primarily focused on graduate certificates in intensive care nursing, writing certificates for practitioners, maintenance of certification in radiation oncology, and the certification of teachers and surgeons. Research on certification in the domain of business and management from an attitudinal?Cbehavioral approach has been lacking. Social psychological theories provide potentially useful tools for explaining how attitudes, intentions, and behaviors are changed. The current study compared four intention-based models??the theory of planned behavior, the theory of self-regulation (TSR), the revised TSR (in which desire is a partial mediator), and the other revised TSR (in which desire is a full mediator)??in terms of their ability to predict the intentions of business and management students to obtain certification in their fields. Participants were drawn from the southern, middle, and northern areas of Taiwan. A structural equation model applied to a sample of 273 undergraduates demonstrated that attitudes, subjective norms, perceived behavioral controls, desires, intentions, and behaviors were associated with certification in business and management domains. The explanatory power of the revised TSR in which desire was a full mediator was superior to that of the competing models. Implications and future directions are discussed.