Botanische und chemische Untersuchungen an pr?historischen Getreidek?rnern aus alten Gr?berfunden

Ohne ZusammenfassungMitteilung aus der Versuchsanstalt des Verbandes Deutscher Müller an der Kgl. Landwirtschaftlichen Hochschule zu Berlin.     

Self-efficacy and mathematics achievement: A study of their relation.

In this study, I investigated the relation between self-efficacy and mathematics achievement when other factors, such as self-concept of math ability, prior task achievement, and prior self-efficacy were taken into account. I assessed self-efficacy over 4 trials in a repeated-measures design with 72 children, aged 9–10 years. I assessed task performance after the first and third self-efficacy assessment. Regression analysis indicated small or no predictive relation between self-efficacy and task performance, depending on task familiarity, when these other factors were included in the analysis. Results of the study lend one to doubt that there is a simple relation between self-efficacy and task performance in the field of mathematics learning. The complexity of self-efficacy, its sources, and consequences are also illustrated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Subcontracting in project-based firms: Do you follow the same pattern across your different projects?

This article analyzes an important dimension in which the organization of the projects performed by the same firm can differ: the insourcing or outsourcing of an activity that needs to be undertaken in each of the different projects. Analyzing the variability of a firm's insourcing or outsourcing decision across its projects gives us a better understanding of the firm's decision-making process in terms of the stability of its choices across projects and the main determinants of that variability. This analysis is valuable because a firm that manages multiple projects can benefit from the careful analysis and consideration of the interactions among and the specificities of its projects. Using a comprehensive database of construction firms and projects, we conclude that firms demonstrate variability in their insource or outsource choices across projects and that this variability is explained by factors such as the number of projects simultaneously undertaken, the variability in a project's complexity, and their market power in local markets. These results suggest that the theories explaining firm boundaries in project-based firms should be expanded to include interrelationships between projects and the individual project characteristics that drive differences in insource or outsource choices.     

Preparation and analysis of poly(l-lactic acid) composites with oligo(d-lactic acid)-grafted cellulose

α-Cellulose extracted from jute fiber was grafted with oligo( d -lactic acid) (ODLA) via a graft polycondensation reaction in the presence of para-toluene sulfonic acid and potassium persulfate in toluene at 130 °C for 9 h under 380 mmHg. ODLA was synthesized by the ring-opening polymerization of d -lactides in the presence of stannous octoate (0.03 wt % lactide) and d -lactic acid at 140 °C for 10 h. Composites of poly( l -lactic acid) (PLLA) with the ODLA-grafted α-cellulose were prepared by the solution-mixing and film-casting methods. The grafting of ODLA onto α-cellulose was confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The analysis of the composites was performed with FTIR spectroscopy, SEM, wide-angle X-ray diffraction, and thermogravimetric analysis. The distribution of the grafted α-cellulose in the composites was uniform and showed better compatibility with PLLA through intermolecular hydrogen bonding. Only homocrystalline structures of PLLA were present in the composites, and the thermal stability increased with increasing percentage of grafted α-cellulose. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47424.     

Good for learning,bad for motivation? A meta-analysis on the effects of computer-supported collaboration scripts

International Journal of Computer-Supported Collaborative Learning - Scripting computer-supported collaborative learning has been shown to greatly enhance learning, but is often criticized for...