Concurrent and longitudinal predictors of calculation skills in preschoolers

Early calculation abilities in preschoolers are predictive of mathematics achievement in subsequent grades (e.g., Jordan et al. 2009). Two studies were conducted to evaluate concurrent and longitudinal predictors of early calculation skills. In the first study, 102 preschoolers (57.8 % female; mean age?=?60.57?±?8.66 months) were given vocabulary, language comprehension, and verbal working memory tasks and a test battery that evaluated components of early number competence (quantity comparison, counting, number line, size seriation, semantic knowledge of digits, visual-spatial memory). The children were also asked to complete early calculation tasks, including addition and subtraction calculations. The results of this task constituted the dependent variable. The results showed that vocabulary, size seriation, and visual-spatial memory were significant concurrent predictors of early calculation competence. In the second study, 43 children completed the early number competence battery at time 1 (53.5 % female; mean age?=?59.30?±?3.46 months) and the linguistic and early calculation tasks at time 2, about 10 months later (mean age?=?69.43?±?3.31 months). The analysis of the longitudinal predictors of early calculation showed significant effects for counting and size seriation. The implications for preschool assessment and intervention are discussed.     

Preservice teachers’ use of contrasting cases in mathematics instruction

Drawing comparisons between students’ alternative solution strategies to a single mathematics problem is a powerful yet challenging instructional practice. We examined 80 preservice teachers’ when asked to design a short lesson when given a problem and two student solutions—one correct and one incorrect. These micro-teaching events were videotaped and coded, revealing that fewer than half of participants (43%) made any explicit comparison or contrasts between the two solution strategies. Those who did were still not likely to use additional support strategies to draw students’ attention to key elements of the comparison. Further, correlations suggest that participants’ mathematical content knowledge may be related to whether participants’ showed contrasting cases but not to whether they used specific pedagogical cues to support those comparisons. While these micro-teaching events differ from the interactive constraints of a classroom, they reveal that participants did not immediately orient toward differing student solutions as a discussion opportunity, and that future instruction on contrasting cases must highlight the utility of this practice.     

Clinical analysis of minimally invasive McKeown esophagectomy in a single center by a single medical group

Objective: McKeown esophagectomy followed by cervical and abdominal procedures has been commonly used for invasive esophageal carcinoma. This minimally-invasive operative procedure in the lateral prone position has been considered to be the most appropriate method. We describe our experiences in minimally invasive McKeown esophagectomy (MIME) for esophageal cancer. Methods: Between March 2016 and February 2018, a total of 82 patients underwent MIME by a single group in our department (a single center). All procedure, operation, oncology, and complication data were reviewed. Results: All MIME procedures were completed successfully, with no conversions to open surgery. The median operative time was 260 min, and median blood loss was 100 ml. The average number of total harvested lymph nodes was 20.1 in the chest and 13.5 in the abdomen. There were no deaths within 30 postoperative days. Twenty cases (24.4%) developed postoperative complications, including anastomotic leak in 4 (4.9%), single lateral recurrent nerve palsy in 4 (4.9%), bilateral recurrent nerve palsy in 1 (1.2%), pulmonary problems in 3 (3.7%), chyle leak in 1 (1.2%), and other complications in 7 (including pleural effusions in 4, incomplete ileus in 2, and neck incision infection in 1; 8.54%). Average postoperative hospitalization time was 12 d. Blood loss, operation time, morbidity rate, and the number of harvested lymph nodes were analyzed by evaluating learning curves in different periods. Significant differences were found in operative time (P=0.006), postoperative hospitalization days (P=0.015), total harvested lymph nodes (P=0.003), harvested thoracic lymph nodes (P=0.006), and harvested abdominal lymph nodes (P=0.022) among different periods. Conclusions: Surgical outcomes following MIME for esophageal cancer are safe and acceptable. The MIME procedure for stages I and II could be performed proficiently and reached an experience plateau after approximately 25 cases.     

„Jeder Schule ihre Lehrer“?

Neue Personalauswahl- und Einstellungsverfahren, an denen die Einzelschulen ma?geblich beteiligt werden, kommen bei der Besetzung von Lehrerstellen in zahlreichen Bundesl?ndern seit Mitte der 1990er-Jahre zur Anwendung und haben mittlerweile die herk?mmlichen zentralen Auswahl- und Zuweisungsverfahren zumindest in einigen von ihnen nahezu vollst?ndig abgel?st. Die Praxis und Wirkung der neuen Auswahlverfahren wurde bislang allerdings nicht systematisch untersucht. In diesem Beitrag werden empirische Befunde einer Untersuchung von Schulen in Nordrhein-Westfalen vorgestellt, die im Jahr 2002 freie Lehrerstellen über das neue Ausschreibungsverfahren besetzt haben. Erfasst wurden unter anderem die in der Praxis angewandten Kriterien der Personalauswahl und die Inhalte der Auswahlgespr?che, die Beurteilung des neuen Auswahl- und Einstellungsverfahrens durch die beteiligten Schulleitungen und Mitglieder der Auswahlkommissionen, Einsch?tzungen und Erfahrungen der neu eingestellten Lehrkr?fte sowie der Verlauf ihrer Berufseinstiegsphase und ihre Bew?hrung am neuen Arbeitsplatz.     

Photoresists for microlithography

Photoresist technology, which is used for micro-patterning exploits changes in properties of polymeric materials, such as their solubility or volatility, upon photo-irradiation. This process has greatly benefitted from the knowledge base of organic chemistry and photo-induced organic transformations. The role of chemistry in the development of photoresists is described in this article.     

Genetics Literacy: Insights From Science Teachers’ Knowledge,Attitude, and Teaching Perceptions

Teachers have a crucial role to play in raising future generations of citizens who are aware of issues in genetics literacy such as gene therapy, cloning, and stem cell research. Teachers’ teaching practices are influenced by their knowledge in genetics literacy and their attitudes towards different issues. Accordingly, this study explored the relationships among middle school science teachers’ background characteristics (gender, teaching experience, self-perceived interest in and self-perceived knowledge of genetics), their genetics literacy levels, their attitudes towards various issues in genetics literacy, and their perceptions of teaching issues in genetics literacy. Data were collected from 435 Turkish middle school science teachers by completing the Genetics Literacy Assessment Inventory, the scale for attitudes towards issues in genetics literacy and perceptions of teaching issues in genetics literacy. The results of canonical correlation analysis suggested that being female, having a high level of interest in genetics, and perceiving oneself as knowledgeable in genetics were associated with higher levels of knowledge in genetics literacy and holding favorable general attitudes. These teachers believed in the necessity of introducing genetics literacy and held higher self-efficacy teaching beliefs regarding the teaching of issues in genetics literacy in their classes. However, they tended to emphasize more impeding factors as well as hold unfavorable attitudes towards gene therapy and gene therapy applications, implying that their attitudes were context dependent.     

Complementary feeding patterns among ethnic groups in rural western China

Objective

This study investigated complementary feeding practices among four ethnic groups (Han, Uygur, Tibetan, and Zhuang) based on a cross-sectional survey in rural western China.

Methods

In 2005, a stratified multistage cluster random sampling method was used to recruit 9712 children (7411 Han, 1032 Uygur, 678 Tibetan, and 591 Zhuang) between 6 and 35 months of age and their mothers from 45 counties in 10 provinces (autonomous regions, municipalities) in western China.

Results

The rates of early introduction (before 6 months) of complementary foods in four ethnic groups (Han, Uygur, Tibetan, and Zhuang) were 71.30%, 95.95%, 82.40%, and 72.30%, respectively. The Infant and Child Feeding Index (ICFI) for Uygur and Tibetan children was lower than that for Han children at all age groups. Uygur children were more likely to have unqualified ICFI compared with Han children in a multivariate logistic regression (odds ratio (OR)=5.138, 95% confidence interval (CI): 4.340–6.084). A higher level of maternal education, greater family wealth, and the availability of complementary feeding educational materials decreased the likelihood of an unqualified ICFI. The nutritional status of children (Han, Tibetan, and Zhuang) with qualified ICFI was better than that for children with unqualified ICFI.

Conclusions

Appropriate interventions are required to improve complementary feeding practices in rural western China.

     

Response-cost punishment with pigeons: Further evidence of response suppression via token loss

Four pigeons responded on a two-component multiple token-reinforcement schedule, in which tokens were produced according to a random-interval 30-sec schedule and exchanged according to a variable-ratio 4 schedule in both components. To assess the effects of contingent token loss, tokens were removed after every second response (i.e., fixed-ratio 2 loss) in one of the components. Response rates were selectively lower in the loss components relative to baseline (no-loss) conditions, as well as to the within-condition no-loss components. Response rates were decreased to a greater degree in the presence of tokens than in their absence. To control for the effects of changes in the density of token and food reinforcement, two parts consisted of additional conditions where food density and token loss were yoked to those in a previous loss condition. In the yoked-food condition, tokens were produced as usual in both components, but the overall density of food reinforcement in one of the components was yoked to that obtained during a previous token-loss condition. In the yoked token-loss condition, tokens were removed during one component of the multiple schedule at a rate that approximately matched the obtained rate of loss from a previous token-loss condition. Response rates in these yoked components were less affected than those in comparable loss components, despite similar densities of token, exchange, and food reinforcement. On the whole, the results support the conclusion that contingent token loss serves as an effective punisher with pigeons.     

Oseen流动中粘性对自由表面波的影响

Based on the complex dispersion relation for the two-dimensional free-surface waves generated by a moving body in the steady Oseen flows, the effect of viscosity on wavelength and wave amplitude was investigated by means of an asymptotic method and a numerical analysis. A comparison between the asymptotic and numerical analysis for the viscous decay factor demonstrates the validity of the perturbation expansions for the wave profile. The numerical result shows that the wavelength of viscous wave is slightly elongated in comparison with that of inviscid wave.