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101.
In this paper we develop a Malmquist productivity index for public sector production characterized by the influence of environmental variables. We extend Johnson and Ruggiero (2011) to the more general case of variable returns to scale to further decompose the Malmquist productivity index into technical, efficiency, scale and environmental change. We apply our model to analyze productivity of Dutch schools using 2002–2007 data. The results indicate that the environment influences the productivity index as well as the technical, efficiency, scale and environmental change components. We see that schools with a moderate classification of environment have the highest productivity numbers. In line with expectations, schools with the worst environment also perform worse and would perform better with an improved environment.  相似文献   
102.
This paper compliments two recent articles by the author in this journal concerning solving the forced harmonic oscillator equation when the forcing is periodic. The idea is to replace the forcing function by its Fourier series and solve the differential equation term-by-term. Herein the convergence of such series solutions is investigated when the forcing function is bounded, piecewise continuous, and piecewise smooth. The series solution and its term-by-term derivative converge uniformly over the entire real line. The term-by-term differentiation produces a series for the second derivative that converges pointwise and uniformly over any interval not containing a jump discontinuity of the forcing function.  相似文献   
103.
In this paper I describe a local instructional theory for supporting the guided reinvention of the group and isomorphism concepts. This instructional theory takes the form of a sequence of key steps as students reinvent these fundamental group theoretic concepts beginning with an investigation of geometric symmetry. I describe these steps and frame them in terms of the theory of Realistic Mathematics Education. Each step of the local instructional theory is illustrated using samples of students’ written work or discussion excerpts.  相似文献   
104.
Recent changes in higher education, especially associated with its massification, have led to calls for more accountability and to an increasing need to evaluate universities’ performance. However, comparing universities with different subject mixes poses some significant problems. In this article, a linear mixed-effect model methodology allowing for random effects at university level is used to measure the productivity of Portuguese public universities, taking into account their subject composition, for a period of five years (1997–2001). The results show that subject mix is an important factor in explaining the variability in productivity between universities. However, even taking account of subject mix, a lot of inefficiency is found in the system, and a significant variability in productivity among universities exists.  相似文献   
105.
Vocal education programs for teachers may prevent the emergence of vocal disorders; however, only a few studies have tried to evaluate the effectiveness of these preventive programs, particularly in the long term. Two hundred and sixty-four subjects, mostly kindergarten and primary school female teachers, participated in a course on voice care, including a theoretical seminar (120 minutes) and a short voice group therapy (180 minutes, small groups of 20 subjects). For 3 months, they had to either attend the vocal ergonomics norms and, as psychological reinforcement, they had to make out a daily report of vocal abuse, or to follow the given exercises for a more efficient vocal technique, reporting on whether the time scheduled was respected or not. The effectiveness of the course was assessed in a group of 21 female teachers through a randomized controlled study. Evaluation comprehended stroboscopy, perceptual and electro-acoustical voice analysis, Voice Handicap Index, and a course benefit questionnaire. A group of 20 teachers matched for age, working years, hoarseness grade, and vocal demand served as a control group. At 3 months evaluation, participants demonstrated amelioration in the global dysphonia rates (P=0.0003), jitter (P=0.0001), shimmer (P=0.0001), MPT (P=0.0001), and VHI (P=0.0001). Twelve months after the course, the positive effects remained, although they were slightly reduced. In conclusion, a course inclusive of two lectures, a short group voice therapy, home-controlled voice exercises, and hygiene, represents a feasible and cost-effective primary prevention of voice disorders in a homogeneous and well-motivated population of teachers.  相似文献   
106.
The solid phase behaviour of HgI2 is reviewed, together with IR and Raman data for the red and the high-temperature yellow forms. New IR transmission, single-crystal reflectance, and Raman data were obtained at temperatures down to 80 K for red HgI2 but no evidence of a temperature-induced transition to HgI2 IV was found.The high pressure results showed a possible break in the slope of the pressure versus frequency plot for the 29 cm?1 Raman mode of red Hgl, at 6 ± 0.5 kbar, close to the reported III/IV phase boundary. Both Raman and far-IR spectra of the high pressure form of yellow HgI2 differ significantly from those of high temperature yellow HgI2 : the two forms are regarded as having different structures. These, and other data, reveal a much closer similarity between the phase diagrams of HgBr2 and HgI2 than has been suspected hitherto.  相似文献   
107.
Since the academic year 2001–2002, inter-laboratory trials for students of Analytical Chemistry in Spanish Universities have been organised by the Department of Analytical Chemistry at the University of Barcelona in collaboration with the Complutense University of Madrid, the University of Cordoba and the University of Huelva. The aim of these exercises is to train students in the use of tools for the assessment and improvement of quality in analytical laboratories.Representative samples of environmental and food analysis, agricultural soils and a type of beer were selected. The ethanol content of the beer and the pH, conductivity, and extractable phosphorus and potassium content in the soil were the chosen analytical parameters.Sample preparation, homogeneity and stability studies, as well as the statistical treatment of data from participants, were carried out by the laboratory Mat Control of the Department of Analytical Chemistry of the University of Barcelona.The paper presented heregives the results obtained after two years of experience.Presented at BERM-9—Ninth International Symposium on Biological and Environmental Reference Materials, June 15–19, 2003, Berlin, Germany.  相似文献   
108.
Before teaching a course, the instructor must identify what she or he intends for the students to learn. For most analytical chemistry instructors, this usually involves an assessment of what methods and techniques to include and at what depth to cover them. There are many other skills, though, that will be important to students for their future success. Most college classes in analytical chemistry are taught in a lecture format. Techniques that can be used to improve the learning that can occur during a lecture are described. An alternative to lecturing is the use of cooperative learning. Cooperative learning offers the potential to develop skills such as teamwork, communication, and problem-solving that are more difficult to impart in a lecture format. The laboratory component of analytical chemistry courses is often an underutilized learning resource. More often than not, the lab is used to demonstrate fundamental wet and instrumental analysis techniques and develop rudimentary laboratory skills. The analytical lab should also be used to develop meaningful problem-solving skills and to demonstrate and have students participate in the entire analytical process. Ways of enhancing the analytical laboratory to include more global skills that are important to career success are described.Received January 12, 2003; accepted March 7, 2003 Published online July 16, 2003  相似文献   
109.
 A report based on the workshop on "Quality Assurance in Daily Practice", organised by the study group "Quality Assurance and Accreditation" from the Division of Analytical Chemistry of the Federation of European Chemical Societies (SGQAA/DAC/FECS) held at the EUROANALYSIS-10 conference in Basle, 6–11 September 1998.  相似文献   
110.
The structures and isomerization of magnesium fluorosilylenoid H2SiFMgF were investigated by ab initio molecular orbital theory. Four equilibrium structures and three isomeric transition states were located and fully optimized at the B3LYP/6-31G(d,p) and G3MP2B3 levels, respectively. Based on the B3LYP/6-31G(d,p) optimized geometries, harmonic frequencies of various structures were obtained and 29Si chemical shifts were calculated. The solvent effects were investigated by means of the polarizable continuum model using THF as a solvent at B3LYP/6-31G(d,p) level. Isomerization paths for isomers were confirmed by intrinsic reaction coordinate calculations. The calculated results show that tetrahedral structure has the lowest energy and is the most stable; tetrahedral, three-membered ring, and p-complex structures are suggested to be the experimentally detectable ones; and σ-complex structure has the highest energy and will not exist.  相似文献   
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